View source for Missouri River

{{Use mdy dates|date=May 2012}}
{{Geobox|River
<!-- *** Heading *** -->
| name = Missouri River
| native_name =
| other_name = Pekitanoui<ref name="GNIS"/>
| other_name1 = Big Muddy<ref name="Spotlight">{{cite web|url=http://www.mostreamteam.org/Documents/Fact%20Sheets/FactSheet2WWW.pdf|title=Spotlight on the Big Muddy|publisher=Missouri Stream Team|accessdate=2012-01-14}}</ref>
| other_name2 = Mighty Mo
| other_name3 = Wide Missouri
| other_name4 = Kícpaarukstiʾ <ref>{{cite web
| title = AISRI Dictionary Database Search--prototype version. "River", Southband Pawnee
| work = American Indian Studies Research Institute
| accessdate = 2012-05-26
| url = http://zia.aisri.indiana.edu/~dictsearch/cgi-bin/testengltoxsrchNP.pl?host=zia&pass=&hasfont=0&srchlang=English&srchstring=river&database=south&srchtype=AND&sortlang=English&sndformat=ra&maxhits=200&find=Run_Search
}}</ref>
| category_hide = 1
<!-- *** Names **** -->
| etymology = The [[Missouri]] tribe, whose name in turn meant “people with wooden canoes”<ref name="GNIS">{{cite gnis|id=756398|name=Missouri River|entrydate=1980-10-24|accessdate=2010-05-06}}</ref>
| nicknames = 
<!-- *** Image *** -->
| image = Lower Missouri River.jpg
| image_caption = A relatively undeveloped reach of the river near [[Rocheport, Missouri]]
| image_size = 300px
| image_alt = A wide river flows between dark forests and low bluffs
<!-- *** Country *** -->
| country = United States
| country_flag =
| state = Montana
| state1 = North Dakota
| state2 = South Dakota
| state3 = Nebraska
| state4 = Iowa
| state5 = Kansas
| state6 = Missouri
| state_flag =
| region =
| district =
| municipality =
<!-- *** Family *** -->
| parent =
| tributary_left = [[Jefferson River|Jefferson]]
| tributary_left1 = [[Dearborn River|Dearborn]]
| tributary_left2 = [[Sun River|Sun]]
| tributary_left3 = [[Marias River|Marias]]
| tributary_left4 = [[Milk River (Montana-Alberta)|Milk]]
| tributary_left5 = [[James River (Dakotas)|James]]
| tributary_left6 = [[Big Sioux River|Big Sioux]]
| tributary_left7 = [[Grand River (Missouri)|Grand]]
| tributary_left8 = [[Chariton River|Chariton]]
| tributary_right = [[Madison River|Madison]]
| tributary_right1 = [[Gallatin River|Gallatin]]
| tributary_right2 = [[Yellowstone River|Yellowstone]]
| tributary_right3 = [[Little Missouri River (North Dakota)|Little Missouri]]
| tributary_right4 = [[Cheyenne River|Cheyenne]]
| tributary_right5 = [[White River (South Dakota)|White]]
| tributary_right6 = [[Niobrara River|Niobrara]]
| tributary_right7 = [[Platte River|Platte]]
| tributary_right8 = [[Kansas River|Kansas]]
| tributary_right9 = [[Osage River|Osage]]
| tributary_right10 = [[Gasconade River|Gasconade]]
| city = [[Great Falls, MT]]
| city1 = [[Bismarck, ND]]
| city2 = [[Pierre, SD]]
| city3 = [[Sioux City, IA]]
| city4 = [[Omaha, NE]]
| city5 = [[Kansas City, KS]]
| city6 = [[Kansas City, MO]]
| city7 = [[St. Louis|St. Louis, MO]]
| landmark =
| river =
<!-- *** River locations *** -->
| source = Hell Roaring Creek, a tributary of the [[Jefferson River]]
| source_location = near [[Brower's Spring]]| source_region =[[Montana]]| source_country =
| source_elevation_imperial = 9100
| source_lat_d = 44| source_lat_m = 32| source_lat_s =31 | source_lat_NS =N
| source_long_d =111 | source_long_m = 27| source_long_s = 53| source_long_EW =W
| source_coordinates_note =<ref>[http://www.topozone.com/map.asp?lat=44.5417&lon=-111.4677&s=25&size=m&u=4&datum=nad83&layer=DRG25] [[United States Geological Survey|USGS]] topographic map of the source</ref><ref name="headwaters"/>
| source1 = [[Firehole River]], a tributary of the [[Madison River]]
| source1_location = Madison Lake| source1_region =[[Yellowstone National Park]], [[Wyoming]]| source1_country =
| source1_elevation_imperial = 8215
| source1_lat_d = 44| source1_lat_m = 20| source1_lat_s = 55| source1_lat_NS =N
| source1_long_d = 110| source1_long_m = 51| source1_long_s = 53| source1_long_EW =W
| source1_coordinates_note=<ref>{{cite gnis|id=1591162|name=Madison Lake|entrydate=1980-04-04|accessdate=2012-01-21}}</ref>
| source_confluence = [[Three Forks of the Missouri]]
| source_confluence_location = [[Three Forks, Montana|Three Forks]]| source_confluence_region = [[Montana]]| source_confluence_country =
| source_confluence_elevation_imperial = 4042
| source_confluence_lat_d = 45| source_confluence_lat_m = 55| source_confluence_lat_s = 39| source_confluence_lat_NS =N
| source_confluence_long_d = 111| source_confluence_long_m = 20| source_confluence_long_s = 39| source_confluence_long_EW =W
| source_confluence_coordinates_note =<ref name="GNIS"/>
| mouth = [[Mississippi River]]
| mouth_location = [[Spanish Lake, Missouri|Spanish Lake]], near [[St. Louis, Missouri|St. Louis]]
| mouth_region = Missouri| mouth_country =
| mouth_elevation_imperial = 404
| mouth_elevation_note =<ref name="GNIS"/>
| mouth_lat_d = 38| mouth_lat_m = 48| mouth_lat_s = 49| mouth_lat_NS =N
| mouth_long_d = 90| mouth_long_m = 07| mouth_long_s = 11| mouth_long_EW =W
| mouth_coordinates_note =<ref name="GNIS"/>
<!-- *** Dimensions *** -->
| length_imperial = 2341| length_orientation =
| length_note =<ref name="modifications">{{cite web
|url=http://infolink.cr.usgs.gov/Science/MoREAP/moreap_brief.htm
|title=Missouri River Environmental Assessment Program Summary
|publisher=U.S. Geological Survey
|accessdate=2010-10-08}}</ref>
| width_imperial = | width_orientation =
| depth_imperial =
| volume_imperial =
| watershed_imperial = 529350
| watershed_note =<ref name="Story"/>
| discharge_imperial = 87520
| discharge_note =<ref name="missouriflow"/>
| discharge_location = [[Hermann, MO]]; [[river mile|RM]] 97.9 (RKM 157.6)
| discharge_max_imperial = 750000
| discharge_max_note =<ref name="peaks">{{cite web|last=Pinter|first=Nicholas|last1=Heine|first1=Reuben A.|url=http://www.grha.net/site/programs/river-study/|title=Hydrologic History of the Lower Missouri River|publisher=Southern Illinois University, Carbondale|work=Geology Department|accessdate=2010-05-08}}</ref>
| discharge_min_imperial = 602
| discharge_min_note=<ref name="missouriflow"/>
<!-- *** Free fields *** -->
| free = | free_type =
<!-- *** Maps *** -->
| map = Missouririvermap.jpg
| map_caption = Map of the Missouri River and its tributaries in<br>North America
| map_size = 280px
| map_background =
| map_locator =
| map_locator_x =
| map_locator_y =
<!-- *** Website *** -->
| website =
| commons =
<!-- *** Footnotes *** -->
| footnotes =
}}

The '''Missouri River''' is the longest river in North America,<ref name="RiversWorld">{{cite web|author=Howard Perlman, USGS |url=http://ga.water.usgs.gov/edu/riversofworld.html |title=Lengths of major rivers, from USGS Water-Science School |publisher=Ga.water.usgs.gov |date=2012-10-31 |accessdate=2012-11-21}}</ref> longest [[tributary]] in the United States and a major waterway of the central United States. Rising in the [[Rocky Mountains]] of western [[Montana]], the Missouri flows east and south for {{convert|2341|mi|km}}<ref name="modifications"/> before entering the [[Mississippi River]] north of [[St. Louis, Missouri|St. Louis]], Missouri. The river takes drainage from a sparsely populated, [[Semi-arid climate|semi-arid]] [[Drainage basin|watershed]] of more than half a million square miles (1,300,000&nbsp;km<sup>2</sup>), which includes parts of ten U.S. states and two Canadian [[Canadian province|provinces]]. When combined with the lower Mississippi River, it forms the [[List of rivers by length|world's fourth longest river system]].<ref name="RiversWorld"></ref>

For over 12,000 years, people have depended on the Missouri and its [[Tributary|tributaries]] as a source of sustenance and transportation. More than ten major groups of [[Indigenous people of the Americas|Native American]]s populated the watershed, most leading a nomadic lifestyle and dependent on enormous [[American bison|buffalo]] herds that once roamed through the [[Great Plains]]. The first Europeans encountered the river in the late seventeenth century, and the region passed through Spanish and French hands before finally becoming part of the United States through the [[Louisiana Purchase]]. The Missouri was long believed to be part of the [[Northwest Passage]] – a water route from the [[Atlantic Ocean|Atlantic]] to the [[Pacific Ocean|Pacific]] – but when [[Lewis and Clark Expedition|Lewis and Clark]] became the first to travel the river's entire length, they confirmed the mythical pathway to be no more than a legend.

The Missouri was one of the main routes for the westward expansion of the United States during the 19th century. The growth of the [[North American fur trade|fur trade]] in the early 1800s laid much of the groundwork as trappers explored the region and blazed trails. [[American pioneer|Pioneer]]s headed west ''en masse'' beginning in the 1830s, first by [[covered wagon]], then by the growing numbers of [[steamboat]]s entering service on the river. Former Native American lands in the watershed were taken over by settlers, leading to some of the most longstanding and violent [[American Indian Wars#Great Plains|wars against indigenous peoples]] in American history. 

During the 20th century, the Missouri River basin was extensively developed for irrigation, flood control and the generation of [[hydroelectric power]]. Fifteen dams impound the [[Mainstem (hydrology)|main stem]] of the river, with hundreds more on tributaries. [[Meander]]s have been cut and the river [[River engineering#Channelization|channelized]] to improve navigation, reducing its length by almost {{convert|200|mi|km}} from pre-development times. Although the lower [[Missouri River Valley|Missouri valley]] is now a populous and highly productive agricultural and industrial region, heavy development has taken its toll on wildlife and fish populations as well as water quality.

==Course==
From the Rocky Mountains of Montana and [[Wyoming]], three streams rise to form the headwaters of the Missouri River. The longest begins near [[Brower's Spring]], {{convert|9100|ft|m}} above sea level, on the southeastern slopes of [[Mount Jefferson (Bitterroot Range)|Mount Jefferson]] in the [[Centennial Mountains]]. Flowing west then north, it runs first in Hell Roaring Creek, then west into the [[Red Rock River (Montana)|Red Rock]]; swings northeast to become the [[Beaverhead River|Beaverhead]], it finally joins with the [[Big Hole River|Big Hole]] to form the [[Jefferson River|Jefferson]]. The [[Firehole River]] originates at Madison Lake in Wyoming's [[Yellowstone National Park]] and joins with the [[Gibbon River|Gibbon]] to form the [[Madison River|Madison]], while the [[Gallatin River]] rises out of Gallatin Lake, also in the national park. These two streams then flow north and northwest into Montana.<ref name="topoquest"/><ref name="ACMEmapper"/>

[[Image:Holter Lake.jpg|thumb|left|alt=View of a deep blue lake surrounded by low mountains|[[Holter Lake]], a reservoir on the upper Missouri River]]
The Missouri River officially starts at the confluence of the Jefferson and Madison in [[Missouri Headwaters State Park]] near [[Three Forks, Montana]], and is joined by the Gallatin a mile (1.6&nbsp;km) downstream. The Missouri then passes through [[Canyon Ferry Lake]], a reservoir west of the [[Big Belt Mountains]]. Issuing from the mountains near [[Cascade, Montana|Cascade]], the river flows northeast to the city of [[Great Falls, Montana|Great Falls]], where it drops over the [[Great Falls of the Missouri]], a series of five substantial waterfalls. It then winds east through a scenic region of canyons and badlands known as the Missouri Breaks, receiving the [[Marias River]] from the west then widening into the [[Fort Peck Lake]] reservoir a few miles above the confluence with the [[Musselshell River]]. Farther on, the river passes through the [[Fort Peck Dam]], and immediately downstream, the [[Milk River (Montana-Alberta)|Milk River]] joins from the north.<ref name="topoquest">{{cite web|author = U.S. Geological Survey|title = United States Geological Survey Topographic Maps| publisher = [[TopoQuest]]| url = http://www.topoquest.com/map.php| accessdate = 2010-05-08}}</ref><ref name="ACMEmapper">{{cite map|publisher=ACME Mapper|title=USGS Topo Maps for United States|cartography=U.S. Geological Survey|accessdate=2010-5-08|url=http://mapper.acme.com/}}</ref>

Flowing eastwards through the plains of eastern Montana, the Missouri receives the [[Poplar River (Saskatchewan-Montana)|Poplar River]] from the north before crossing into [[North Dakota]] where the [[Yellowstone River]], its greatest tributary by volume, joins from the southwest. At the confluence, the Yellowstone is actually the larger river.{{#tag:ref|The Missouri's flow at [[Culbertson, Montana]], {{convert|25|mi|km|abbr=on}} above the confluence of the two rivers, is about {{convert|9820|cuft/s|m3/s|abbr=on}}<ref>{{cite web|url=http://wdr.water.usgs.gov/wy2010/pdfs/06185500.2010.pdf|title=USGS Gage #06185500 on the Missouri River near Culbertson, MT|publisher=U.S. Geological Survey|work=National Water Information System|date=1941–2010|accessdate=2011-07-04}}</ref> and the Yellowstone's discharge at [[Sidney, Montana]], roughly the same distance upstream along that river, is about {{convert|12370|cuft/s|m3/s|abbr=on}}.<ref>{{cite web|url=http://wdr.water.usgs.gov/wy2010/pdfs/06329500.2010.pdf|title=USGS Gage #06329000 on the Yellowstone River near Sidney, MT|publisher=U.S. Geological Survey|work=National Water Information System|date=1911–2010|accessdate=2011-07-04}}</ref>|group=n}} The Missouri then meanders east past [[Williston, North Dakota|Williston]] and into [[Lake Sakakawea]], the reservoir formed by [[Garrison Dam]]. Below the dam the Missouri receives the [[Knife River]] from the west and flows south to [[Bismarck, North Dakota|Bismarck]], the capital of North Dakota, where the [[Heart River (North Dakota)|Heart River]] joins from the west. It slows into the [[Lake Oahe]] reservoir just before the [[Cannonball River]] confluence. While it continues south, eventually reaching [[Oahe Dam]] in [[South Dakota]], the [[Grand River (South Dakota)|Grand]], [[Moreau River|Moreau]] and [[Cheyenne River]]s all join the Missouri from the west.<ref name="topoquest"/><ref name="ACMEmapper"/>

The Missouri makes a bend to the southeast as it winds through the Great Plains, receiving the [[Niobrara River]] and many smaller tributaries from the southwest. It then proceeds to form the boundary of South Dakota and [[Nebraska]], then after being joined by the [[James River (Dakotas)|James River]] from the north, forms the [[Iowa]]–Nebraska boundary. At [[Sioux City]] the [[Big Sioux River]] comes in from the north. The Missouri flows south to the city of [[Omaha, Nebraska|Omaha]] where it receives its longest tributary, the [[Platte River]], from the west.<ref>Twentieth Century Encyclopædia: A Library of Universal Knowledge, Vol. 5, p. 2399</ref> Downstream, it begins to define the Nebraska–Missouri border, then flows between Missouri and [[Kansas]]. The Missouri swings east at [[Kansas City, Missouri|Kansas City]], where the [[Kansas River]] enters from the west, and so on into north-central Missouri. It passes south of [[Columbia, Missouri|Columbia]] and receives the [[Osage River|Osage]] and [[Gasconade River|Gasconade]] Rivers from the south downstream of [[Jefferson City, Missouri|Jefferson City]]. The river then rounds the northern side of [[St. Louis, Missouri|St. Louis]] to join the Mississippi River on the border between Missouri and [[Illinois]].<ref name="topoquest"/><ref name="ACMEmapper"/>

==Watershed==
[[File:Missouri-bismarck-nd-2004-1.jpg|thumb|alt=The sun low over the horizon over a body of water surrounded by dark vegetation|The Missouri in North Dakota, which was the furthest upstream that French explorers managed on the river]]
{{quote box|width=24em|bgcolor=|align=left|quote= There is only one river with a personality, a sense of humor, and a woman's caprice; a river that goes traveling sidewise, that interferes in politics, rearranges geography, and dabbles in real estate; a river that plays hide and seek with you today and tomorrow follows you around like a pet dog with a dynamite cracker tied to his tail. That river is the Missouri.<br>-George Fitch<ref>Athearn, p. 89</ref>}}
With a drainage basin spanning {{convert|529350|sqmi|km2}},<ref name="Story">{{cite web
|url=http://infolink.cr.usgs.gov/The_River/MORstory.htm
|title=The Missouri River Story
|publisher=U.S. Geological Survey
|work=Columbia Environmental Research Center
|accessdate=2010-04-10}}</ref>
the Missouri's catchment encompasses nearly one-sixth of the area of the United States<ref>{{cite web
|url=http://www.cerc.usgs.gov/ScienceTopics.aspx?ScienceTopicId=10
|title=Missouri River
|publisher=U.S. Geological Survey
|work=Columbia Environmental Research Center
|date=2009-09-08
|accessdate=2010-05-10}}</ref> or just over five percent of the continent of North America.<ref>{{cite web
|url=http://www.britannica.com/EBchecked/topic/418612/North-America
|title=North America
|publisher=Encyclopædia Britannica
|accessdate=2010-05-10}}</ref> Comparable to the size of the Canadian province of [[Quebec]], the watershed encompasses most of the central Great Plains, stretching from the Rocky Mountains in the west to the [[Mississippi River Valley]] in the east and from the southern extreme of western Canada to the border of the [[Arkansas River]] watershed. Compared with the Mississippi River above their confluence, the Missouri is twice as long{{#tag:ref|The Mississippi River flows for approximately {{convert|1172|mi|km}} above St. Louis,<ref name="ACMEmapper"/> which is just over half of the Missouri's length.|group=n}} and drains an area three times as large.{{#tag:ref|The Mississippi drains an area of {{convert|172200|mi2|km2|abbr=on}} above the confluence with the Missouri River.<ref name="USGS"/>|group=n}} The Missouri accounts for 45&nbsp;percent of the annual flow of the Mississippi past St. Louis, and as much as 70&nbsp;percent in certain droughts.<ref name="missouriflow">{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/06934500.2009.pdf|title=USGS Gage #06934500 on the Missouri River at Hermann, Missouri: Water-Data Report 2009|publisher=U.S. Geological Survey|work=National Water Information System|date=1897–2009|accessdate=2010-08-24}}</ref><ref name="MississippiStLouis">{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/07010000.2009.pdf|title=USGS Gage #07010000 on the Mississippi River at St. Louis, Missouri: Water-Data Report 2009|publisher=U.S. Geological Survey|work=National Water Information System|date=1861–2009|accessdate=2010-08-24}} Note: This gauge is just below the Missouri confluence, so the Missouri discharge was subtracted from {{convert|190000|cuft/s|m3/s}} to get this amount.</ref>

As of 1990, the Missouri River watershed was home to about 12 million people.<ref name="Story"/><ref name="MainstemSystem"/> This includes the entire population of the U.S. state of Nebraska, parts of the U.S. states of Colorado, Iowa, Kansas, Minnesota, Missouri, Montana, North Dakota, South Dakota, and Wyoming, and small southern portions of the Canadian provinces of [[Alberta]] and [[Saskatchewan]].<ref name="Story"/> The watershed's largest city is [[Denver]], Colorado, with a population of more than six hundred thousand. Denver is the main city of the [[Front Range Urban Corridor]] whose cities had a combined population of over four million in 2005,<ref>{{cite news
|url=http://americancity.org/magazine/article/wyoming-metropolis-crane/
|author=Crane, Gabe
|title=Wyoming Metropolis?
|work=Next American City
|year=2007
|accessdate=2012-01-17
|archiveurl=http://web.archive.org/web/20101211074753/http://americancity.org/magazine/article/wyoming-metropolis-crane/
|archivedate=2010-12-11}}</ref> making it the largest metropolitan area in the Missouri River basin.<ref name="MainstemSystem"/> Other major population centers – mostly located in the southeastern portion of the watershed – include [[Omaha, Nebraska]], situated north of the confluence of the Missouri and Platte Rivers; [[Kansas City, Missouri]] – [[Kansas City, Kansas]], located at the confluence of the Missouri with the Kansas River, and the St. Louis metropolitan area, situated south of the Missouri River just above its mouth on the Mississippi.<ref name="ACMEmapper"/> In contrast, the northwestern part of the watershed is sparsely populated. However, many northwestern cities, such as [[Billings, Montana]], are among the fastest growing in the Missouri basin.<ref name="MainstemSystem"/>

With more than {{convert|170000|mi2|km2}} under the plow, the Missouri River watershed includes roughly one-fourth of all the agricultural land in the United States, providing more than a third of the country's wheat, flax, barley and oats. However, only {{convert|11000|mi2|km2}} of farmland in the basin is irrigated. A further {{convert|281000|mi2|km2}} of the basin is devoted to the raising of livestock, mainly cattle. Forested areas of the watershed, mostly [[Second-growth forest|second-growth]], total about {{convert|43700|mi2|km2}}. Urban areas, on the other hand, comprise less than {{convert|13000|mi2|km2}} of land. Most built-up areas are located along the main stem and a few major tributaries, including the Platte and Yellowstone Rivers.<ref name="MainstemSystem"/><ref>{{cite article
|author=DeFranco, Anthony
|title=No More Floods! Build The Missouri River Development Project
|url=http://www.21stcenturysciencetech.com/Articles_2011/MissouriRiverProject.pdf
|publisher=21st Century Science and Technology
|work=New Federalist American Almanac
|date=1994-06-27
|accessdate=2012-01-17}}</ref>

Elevations in the watershed vary widely, ranging from just over {{convert|400|ft|m}} at the Missouri's mouth<ref name="GNIS"/> to the {{convert|14278|ft|m|adj=on}} summit of [[Grays Peak]] in central Colorado.<ref name="MainstemSystem">{{cite web
|url=http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1070&context=usarmyceomaha
|title=Missouri River Mainstem Reservoir System Master Water Control Manual
|publisher=University of Nebraska Lincoln Digital Commons
|work=U.S. Army Corps of Engineers
|date=2006-01-01
|accessdate=2012-01-15}}</ref><ref>{{cite web
|url=http://egsc.usgs.gov/isb/pubs/booklets/elvadist/elvadist.html#14,000
|title=Elevations and Distances in the United States
|publisher=U.S. Geological Survey
|work=Eastern Geographic Science Center
|date=2005-04-29
|accessdate=2010-10-08}}</ref> The river itself drops a total of {{convert|8626|ft|m}} from Brower's Spring, the farthest source. Although the plains of the watershed have extremely little local vertical relief, the land rises about 10 feet per mile (1.9 m/km) from east to west. The elevation is less than {{convert|500|ft|m}} at the eastern border of the watershed, but is over {{convert|3000|ft|m}} above sea level in many places at the base of the Rockies.<ref name="ACMEmapper"/>

The Missouri's drainage basin has highly variable weather and rainfall patterns, Overall, the watershed is defined by a [[Continental climate]] with warm, wet summers and harsh, cold winters. Most of the watershed receives an average of {{convert|8|to|10|in|mm}} of precipitation each year.<ref name="MainstemSystem"/> However, the westernmost portions of the basin in the Rockies as well as southeastern regions in Missouri may receive as much as {{convert|40|in|mm}}.<ref name="MainstemSystem"/> The vast majority of precipitation occurs in winter, although the upper basin is known for short-lived but intense summer [[thunderstorm]]s such as the one which produced the [[Black Hills flood|1972 Black Hills flood]] through [[Rapid City, South Dakota]].<ref>{{cite web
|url=http://pubs.usgs.gov/fs/fs-037-02/
|title= The 1972 Black Hills-Rapid City Flood Revisited
|publisher=U.S. Geological Survey
|accessdate=2012-01-15
|author=Carter, Janet M.; Williamson, Joyce E.; Teller, Ralph W.}}</ref> Winter temperatures in Montana, Wyoming and Colorado may drop as low as {{convert|-60|F|C}}, while summer highs in Kansas and Missouri have reached {{convert|120|F|C}} at times.<ref name="MainstemSystem"/>

As one of the continent's most significant river systems,<ref name="watershedmap">{{cite web
| title= Watersheds (map)
| publisher = Commission for Environmental Cooperation
| year= 2006
| url= http://www.cec.org/naatlas/img/NA-Watersheds.gif
| archiveurl= http://web.archive.org/web/20080227060842/http://www.cec.org/naatlas/img/NA-Watersheds.gif
| archivedate= 2008-02-27
| accessdate= 2008-09-12}}</ref> the Missouri's drainage basin borders on many other major watersheds of the United States and Canada. The [[Continental Divide of the Americas|Continental Divide]], running along the spine of the Rocky Mountains, forms most of the western border of the Missouri watershed.<ref name="watershedmap"/> The [[Clark Fork (river)|Clark Fork]] and [[Snake River]], both part of the [[Columbia River]] basin, drain the area west of the Rockies in Montana, [[Idaho]] and western Wyoming. The Columbia, Missouri and [[Colorado River]] watersheds meet at [[Three Waters Mountain]] in Wyoming's [[Wind River Range]].<ref>{{cite web
|author=Gonzalez, Mark A.
|url=http://nationalatlas.gov/articles/geology/a_continentalDiv.html
|title=Continental Divides in North Dakota and North America
|publisher=The National Atlas
|work=North Dakota Geological Survey Newsletter
|year=2003
|accessdate=2012-01-14}}</ref> South of there, the Missouri basin is bordered on the west by the drainage of the [[Green River (Wyoming)|Green River]], a tributary of the Colorado, then on the south by the mainstem of the Colorado. Both the Colorado and Columbia Rivers flow to the Pacific Ocean. However, a large [[endorheic|endorheic drainage]] called the Great Divide Basin exists between the Missouri and Green watersheds in western Wyoming. This area is sometimes counted as part of the Missouri River watershed, even though its waters do not flow to either side of the Continental Divide.<ref>{{cite web|url=http://www.wsgs.uwyo.edu/StratWeb/GreatDivideBasin/Default.aspx|title=Great Divide Basin|publisher=Wyoming State Geological Survey|accessdate=2011-03-16}}</ref>

To the north, the much lower [[Laurentian Divide]] separates the Missouri River watershed from those of the [[Oldman River]], a tributary of the [[South Saskatchewan River]], as well as the [[Souris River|Souris]], [[Sheyenne River|Sheyenne]], and smaller tributaries of the [[Red River of the North]]. All of these streams are part of Canada's [[Nelson River]] drainage basin, which empties into [[Hudson Bay]]. There are also several large endorheic basins between the Missouri and Nelson watersheds in southern Alberta and Saskatchewan.<ref name="watershedmap"/> The [[Minnesota River|Minnesota]] and [[Des Moines River|Des Moines]] Rivers, tributaries of the upper Mississippi, drain most of the area bordering the eastern side of the Missouri River basin. Finally, on the south, the [[The Ozarks|Ozark Mountains]] and other low divides through central Missouri, Kansas and Colorado separate the Missouri watershed from those of the [[White River (Arkansas)|White River]] and Arkansas River, also tributaries of the Mississippi River.<ref name="watershedmap"/>

===Major tributaries===
[[Image:Yellowstone River, flowing through Paradise Valley.jpg|thumb|240px|alt=A river flows past grass-covered banks, trees are in the midground|The Yellowstone River, the fifth longest tributary of the Missouri, which it joins in North Dakota]]
{{Main|List of tributaries of the Missouri River}}
Over 95 significant tributaries and hundreds of smaller ones feed the Missouri River, with most of the larger ones coming in as the river draws close to the mouth.<ref>{{cite web
|author=Stone, Clifton
|url=http://www3.northern.edu/natsource/HABITATS/Missio1.htm
|title=Missouri River
|publisher=Northern State University
|work=The Natural Source
|accessdate=2011-07-10}}</ref>  Most rivers and streams in the Missouri River basin flow from west to east, following the incline of the Great Plains; however, some eastern tributaries such as the James, [[Big Sioux River|Big Sioux]] and [[Grand River (Missouri)|Grand]] River systems flow from north to south.<ref name="MainstemSystem"/> 

The Missouri's largest tributaries by runoff are the Yellowstone in Montana and Wyoming, the Platte in Wyoming, Colorado, and Nebraska, and the [[Kansas River|Kansas]]–[[Republican River|Republican]]/[[Smoky Hill River|Smoky Hill]] and Osage in Kansas and Missouri. Each of these tributaries drains an area greater than {{convert|50000|mi2|km2}}, and has an average discharge greater than {{convert|5000|cuft/s|m3/s|abbr=on}}.<ref name="USGS"/><ref name="USGSrivers"/> The Yellowstone River has the highest discharge, even though the Platte is longer and drains a larger area. In fact, the Yellowstone's flow is about {{convert|13800|cuft/s|m3/s|abbr=on}}<ref name="Yellowstoneflow">{{cite web
|url=http://www.sage.wisc.edu/riverdata/scripts/station_table.php?qual=32&filenum=2845
|title=Yellowstone River at Sidney, Montana
|publisher=Center for Sustainability and the Global Environment
|work=River Discharge Database
|date=1965-1984
|accessdate=2010-05-10}}</ref> – accounting for sixteen percent of total runoff in the Missouri basin and nearly double that of the Platte.<ref name="Platteflow">{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/06805500.2009.pdf|title=USGS Gage #06805500 on the Platte River at Louisville, NE|publisher=U.S. Geological Survey|work=National Water Information System|date=1953–2009|accessdate=2011-03-05}}</ref> On the other end of the scale is the tiny [[Roe River]] in Montana, which at {{convert|201|ft|m}} long is commonly held to be the world's shortest river.<ref>McFarlan and McWhirter, p. 32</ref>

{| class="wikitable sortable collapsible collapsed"  style="float:right; width:47%;"
|-
!colspan="7"|Longest tributaries of the Missouri River
|- style="font-size:9pt; text-align:center;"
!Name
!colspan="2"|Length
!colspan="2"|[[Drainage basin|Watershed]]
!colspan="2"|[[Discharge (hydrology)|Discharge]]
|- style="font-size:9pt; text-align:center;"
! style="background:#faebd7;"|
! style="background:ivory;"|'''mi'''
!'''km'''
! style="background:ivory;"|'''mi<sup>2</sup>'''
!'''km<sup>2</sup>'''
! style="background:ivory;"|'''[[Cubic feet per second|ft<sup>3</sup>/s]]'''
!'''[[Cubic meters per second|m<sup>3</sup>/s]]'''
|- style="font-size:9pt; text-align:center;"
! scope="row" style="background:#faebd7;"|[[Platte River]]
| style="background:ivory;"|{{nts|1,061}}<ref name="ACMEmapper"/><ref name="USGSrivers">{{cite web|first=J.C.|last=Kammerer|url=http://pubs.usgs.gov/of/1987/ofr87-242/|title=Largest Rivers in the United States|publisher=U.S. Geological Survey|date=1990-05|accessdate=2011-03-05}}</ref>
|1,708
| style="background:ivory;"|{{nts|84,910}}<ref name="USGS">{{cite web|title=Boundary Descriptions and Names of Regions, Subregions, Accounting Units and Cataloging Units |url=http://water.usgs.gov/GIS/huc_name.html |publisher=U.S. Geological Survey |accessdate=2011-03-05}}</ref>
|{{nts|219,900}}
| style="background:ivory;"|{{nts|7,037}}<ref name="Platteflow"/>
|199
|- style="font-size:9pt; text-align:center;"
! scope="row" style="background:#faebd7;"|[[Kansas River]]
| style="background:ivory;"|{{nts|749}}<ref name="USGSrivers"/><ref name="NationalMap">{{cite web| url=http://viewer.nationalmap.gov/viewer/|title=The National Map|publisher=U.S. Geological Survey|accessdate=2011-03-05}}</ref>
|1,205
| style="background:ivory;"|{{nts|59,500}}<ref name="USGS"/>
|{{nts|154,000}}
| style="background:ivory;"|{{nts|7,367}}<ref>{{cite web|url=http://wdr.water.usgs.gov/wy2010/pdfs/06892350.2010.pdf|title=USGS Gage #06892350 on the Kansas River at DeSoto, KS|publisher=U.S. Geological Survey|work=National Water Information System|date=1917–2010|accessdate=2011-03-05}}</ref>
|209
|- style="font-size:9pt; text-align:center;"
! scope="row" style="background:#faebd7;"|[[Milk River (Montana-Alberta)|Milk River]]
| style="background:ivory;"|{{nts|729}}<ref name="NationalMap"/>
|1,170
| style="background:ivory;"|{{nts|15,300}}<ref name="USGS"/>
|{{nts|39,600}}
| style="background:ivory;"|{{nts|618}}<ref>{{cite web|url=http://wdr.water.usgs.gov/wy2010/pdfs/06174500.2010.pdf|title=USGS Gage #06174500 on the Milk River at Nashua, MT|publisher=U.S. Geological Survey|work=National Water Information System|date=1940–2010|accessdate=2011-03-05}}</ref>
|17.5
|- style="font-size:9pt; text-align:center;"
! scope="row" style="background:#faebd7;"|[[James River (Dakotas)|James River]]
| style="background:ivory;"|{{nts|710}}<ref name="NationalMap"/>
|1,140
| style="background:ivory;"|{{nts|21,500}}<ref name="USGS"/>
|{{nts|55,700}}
| style="background:ivory;"|{{nts|646}}<ref>{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/06478500.2009.pdf|title=USGS Gage #06478500 on the James River near Scotland, SD|publisher=U.S. Geological Survey|work=National Water Information System|date=1928–2009|accessdate=2011-03-05}}</ref>
|18.3
|- style="font-size:9pt; text-align:center;"
! scope="row" style="background:#faebd7;"|[[Yellowstone River]]
| style="background:ivory;"|{{nts|702}}<ref name="ACMEmapper"/><ref>{{cite web|last=Miller|first=Kirk A.|url=http://pubs.usgs.gov/wri/wri984269/surwater.html|title=Surface Water|publisher=U.S. Geological Survey|work=Environmental Setting of the Yellowstone River Basin, Montana, North Dakota, and Wyoming|year=1999|accessdate=2011-03-06}}</ref>
|1,130
| style="background:ivory;"|{{nts|70,000}}<ref name="USGS"/>
|{{nts|180,000}}
| style="background:ivory;"|{{nts|13,800}}<ref name="Yellowstoneflow"/>
|391
|- style="font-size:9pt; text-align:center;"
! scope="row" style="background:#faebd7;"|[[White River (South Dakota)|White River]]
| style="background:ivory;"|{{nts|580}}<ref name="NationalMap"/>
|933
| style="background:ivory;"|{{nts|10,200}}<ref name="Whiteflow">{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/06452000.2009.pdf|title=USGS Gage #06452000 on the White River near Oacoma, SD|publisher=U.S. Geological Survey|work=National Water Information System|date=1928–2009|accessdate=2011-03-05}}</ref>
|{{nts|26,420}}
| style="background:ivory;"|{{nts|570}}<ref name="Whiteflow"/>
|16.1
|- style="font-size:9pt; text-align:center;"
! scope="row" style="background:#faebd7;"|[[Niobrara River]]
| style="background:ivory;"|{{nts|568}}<ref name="NationalMap"/>
|914
| style="background:ivory;"|{{nts|13,900}}<ref name="USGS"/>
|{{nts|36,000}}
| style="background:ivory;"|{{nts|1,720}}<ref>{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/06465500.2009.pdf|title=USGS Gage #06465500 on the Niobrara River near Verdel, NE|publisher=U.S. Geological Survey|work=National Water Information System|date=1928–2009|accessdate=2011-03-05}}</ref>
|48.7
|- style="font-size:9pt; text-align:center;"
! scope="row" style="background:#faebd7;"|[[Little Missouri River (North Dakota)|Little Missouri River]]
| style="background:ivory;"|{{nts|560}}<ref name="NationalMap"/>
|900
| style="background:ivory;"|{{nts|9,550}}<ref name="USGS"/>
|{{nts|24,700}}
| style="background:ivory;"|{{nts|533}}<ref>{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/06337000.2009.pdf|title=USGS Gage #06337000 on the Little Missouri River near Watford City, ND|publisher=U.S. Geological Survey|work=National Water Information System|date=1935–2009|accessdate=2011-03-05}}</ref>
|15.1
|- style="font-size:9pt; text-align:center;"
! scope="row" style="background:#faebd7;"|[[Osage River]]
| style="background:ivory;"|{{nts|493}}<ref name="ACMEmapper"/>
|793
| style="background:ivory;"|{{nts|14,800}}<ref name="USGS"/>
|{{nts|38,300}}
| style="background:ivory;"|{{nts|11,980}}<ref>{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/06926510.2009.pdf|title=USGS Gage #06926510 on the Osage River below St. Thomas, MO|publisher=U.S. Geological Survey|work=National Water Information System|date=1996–2009|accessdate=2011-03-05}}</ref>
|339
|- style="font-size:9pt; text-align:center;"
! scope="row" style="background:#faebd7;"|[[Big Sioux River]]
| style="background:ivory;"|{{nts|419}}<ref name="NationalMap"/>
|674
| style="background:ivory;"|{{nts|8,030}}<ref name="USGS"/>
|{{nts|20,800}}
| style="background:ivory;"|{{nts|1,320}}<ref>{{cite web|url=http://wdr.water.usgs.gov/wy2010/pdfs/06485500.2010.pdf|title=USGS Gage #06485500 on the Big Sioux River at Akron, IA|publisher=U.S. Geological Survey|work=National Water Information System|date=1929–2009|accessdate=2012-01-10}}</ref>
|37.4
|}

The table on the right lists the ten longest tributaries of the Missouri, along with their respective catchment areas and flows. Length is measured to the hydrologic source, regardless of naming convention. The main stem of the Kansas River, for example, is {{convert|148|mi|km}} long.<ref name="NationalMap"/> However, including the longest headwaters tributaries, the {{convert|453|mi|km|adj=on}} Republican River and the {{convert|156|mi|km|adj=on}} [[Arikaree River]], brings the total length to {{convert|749|mi|km}}.<ref name="NationalMap"/> Similar naming issues are encountered with the Platte River, whose longest tributary, the [[North Platte River]], is more than twice as long as its mainstream.<ref name="NationalMap"/>

The Missouri's headwaters above Three Forks extend much farther upstream than the main stem. Measured to the farthest source at Brower's Spring, the Jefferson River is {{convert|298|mi|km}} long.<ref name="MainstemSystem"/> Thus measured to its highest headwaters, the Missouri River stretches for {{convert|2639|mi|km}}. When combined with the lower Mississippi, the Missouri and its headwaters form part of the [[List of rivers by length|fourth-longest river system in the world]], at {{convert|3745|mi|km}}.<ref name="headwaters">{{cite article
|authors=Nell, Donald F.; Demetriades, Anthony
|url=http://fwp.mt.gov/mtoutdoors/HTML/articles/2005/MissouriSource.htm
|title=The True Utmost Reaches of the Missouri: Were Lewis and Clark wrong when they identified the source of this great river?
|work=Montana Outdoors
|issue=2005–07 to 08
|accessdate=2012-01-14}}</ref>

===Discharge===
[[File:Corp of Eng. 6-16-11A 267.JPG|thumb|Nebraska's [[Fort Calhoun Nuclear Generating Station]] was inundated when the Missouri River [[2011 Missouri River Floods|flooded in 2011]]|alt=Aerial view of farms and a power station in a rural area partly inundated by a river that has overflowed its banks]]
By [[Discharge (hydrology)|discharge]], the Missouri is the ninth largest river of the United States, after the Mississippi, [[St. Lawrence River|St. Lawrence]], [[Ohio River|Ohio]], Columbia, [[Niagara River|Niagara]], [[Yukon River|Yukon]], [[Detroit River|Detroit]], and [[St. Clair River|St. Clair]]. The latter two, however, are sometimes considered part of a strait between [[Lake Huron]] and [[Lake Erie]].<ref name="USrivers">{{cite web
|last=Kammerer
|first=J.C.
|url=http://pubs.usgs.gov/of/1987/ofr87-242/
|title=Largest Rivers in the United States
|publisher=U.S. Geological Survey
|date=1990-05
|accessdate=2010-10-01}}</ref> Among rivers of North America as a whole, the Missouri is thirteenth largest, after the Mississippi, [[Mackenzie River|Mackenzie]], St. Lawrence, Ohio, Columbia, Niagara, Yukon, Detroit, St. Clair, [[Fraser River|Fraser]], [[Slave River|Slave]], and [[Koksoak River|Koksoak]].<ref name="USrivers"/><ref>{{cite web
|url=http://atlas.nrcan.gc.ca/site/english/learningresources/facts/rivers.html
|title=Rivers
|publisher=Natural Resources Canada
|work=The Atlas of Canada
|date=2010-10-25
|accessdate=2010-11-28}}</ref>

As the Missouri drains a predominantly semi-arid region, its discharge is much lower and more variable than other North American rivers of comparable length. Before the construction of dams, the river flooded twice each year – once in the "April Rise" or "[[Freshet|Spring Fresh]]", with the melting of snow on the plains of the watershed, and in the "June Rise", caused by snowmelt and summer rainstorms in the Rocky Mountains. The latter was far more destructive, with the river increasing to over ten times its normal discharge in some years.<ref>{{cite news
|author=Schneiders, Robert Kelley
|url=http://bismarcktribune.com/news/columnists/article_ede94e28-8df1-11e0-a6bc-001cc4c002e0.html
|title=The Great Missouri River Flood of 2011
|work=Bismarck Tribune
|date=2011-06-05
|accessdate=2012-01-14}}</ref><ref>{{cite web
|url=http://dnr.mo.gov/pubs/pub2018.pdf
|title=The Missouri River –  Water Protection Program fact sheet
|publisher=Missouri Department of Natural Resources
|accessdate=2012-01-14}}</ref> The Missouri's discharge is affected by over 17,000 reservoirs with an aggregate capacity of some 141 million [[acre foot|acre-feet]] (173.9&nbsp;km<sup>3</sup>).<ref name="MainstemSystem"/> By providing flood control, the reservoirs dramatically reduce peak flows and increase low flows. Evaporation from reservoirs significantly reduces the river's runoff, causing an annual loss of over three million acre-feet (3.8&nbsp;km<sup>3</sup>) from mainstem reservoirs alone.<ref name="MainstemSystem"/>

{| style="float:left; width:15em; border:1=0px solid #a0a0a0; padding:0; background:#fff; text-align:center;"
|-
|
{| class="wikitable collapsible collapsed"
!colspan=3|Monthly discharge at<br>[[Hermann, Missouri|Hermann, MO]]<ref>{{cite web|url=http://nwis.waterdata.usgs.gov/nwis/monthly/?referred_module=sw&amp;site_no=06934500&amp;por_06934500_6=834553,00060,6,1928-10,2010-08&amp;format=html_table&amp;date_format=YYYY-MM-DD&amp;rdb_compression=file&amp;submitted_form=parameter_selection_list|title=USGS Gage #06934500 on the Missouri River at Hermann, Missouri: Monthly Average Flow|publisher=U.S. Geological Survey|work=National Water Information System|date=1957–2010|accessdate=2010-10-08}}</ref>
|-
!Month
![[Cubic feet per second|cfs]]
![[Cubic meters per second|m<sup>3</sup>/s]]
|-
|Jan.||52,400||1,490
|-
|Feb.||67,900||1,920
|-
|Mar.||96,300||2,730
|-
|Apr.||119,000||3,370
|-
|May||125,000||3,540
|-
|Jun.||124,000||3,510
|-
|Jul.||101,000||2,860
|-
|Aug.||73,600||2,080
|-
|Sep.||75,400||2,140
|-
|Oct.||76,500||2,170
|-
|Nov.||76,000||2,150
|-
|Dec.||61,000||1,730
|}

{| class="wikitable collapsible collapsed"
!colspan=3|Average discharge at<br>selected cities<br><ref name="missouriflow"/><ref name="KSCdischarge"/><ref>{{cite web | title = Missouri River at Great Falls, Montana| publisher = Center for Sustainability and the Global Environment (SAGE), Gaylord Nelson Institute for Environmental Studies, University of Wisconsin–Madison |work=River Discharge Database| url = http://www.sage.wisc.edu/riverdata/scripts/station_table.php?qual=32&filenum=1454 |accessdate=2012-01-19}}</ref><ref>{{cite web|url=http://wdr.water.usgs.gov/wy2010/pdfs/06440000.2010.pdf|title=USGS Gage #06440000 on the Missouri River at Pierre, SD|publisher=U.S. Geological Survey|work=National Water Information System|date=1934–1965|accessdate=2012-01-19}}</ref><ref>{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/06486000.2009.pdf|title=USGS Gage #06486000 on the Missouri River at Sioux City, IA|publisher=U.S. Geological Survey|work=National Water Information System|date=1953–2009|accessdate=2010-10-09}}</ref><ref>{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/06610000.2009.pdf|title=USGS Gage #06610000 on the Missouri River at Omaha, NE|publisher=U.S. Geological Survey|work=National Water Information System|date=1953–2009|accessdate=2010-10-09}}</ref><ref>{{cite web|url=http://wdr.water.usgs.gov/wy2009/pdfs/06909000.2009.pdf|title=USGS Gage #06909000 on the Missouri River at Boonville, MO|publisher=U.S. Geological Survey|work=National Water Information System|date=1958–2009|accessdate=2010-10-09}}</ref>
|-
!City
![[Cubic feet per second|cfs]]
![[Cubic meters per second|m<sup>3</sup>/s]]
|-
|[[Great Falls, Montana|Great Falls, MT]]
|10,300
|292
|-
|[[Pierre, South Dakota|Pierre, SD]]
|26,500
|750
|-
|[[Sioux City, Iowa|Sioux City, IA]]
|28,670
|812
|-
|[[Omaha, Nebraska|Omaha, NE]]
|32,190
|912
|-
|[[Kansas City, Missouri|Kansas City, MO]]
|55,400
|1,570
|-
|[[Boonville, Missouri|Boonville, MO]]
|67,160
|1,902
|-
|[[Hermann, Missouri|Hermann, MO]]
|87,520
|2,478
|}
|}

The [[United States Geological Survey]] operates fifty-one [[stream gauge]]s along the Missouri River. The river's average discharge at Bismarck, {{convert|1314.5|mi|km}} from the mouth, is {{convert|21920|cuft/s|m3/s|abbr=on}}. This is from a drainage area of {{convert|186400|mi2|km2|abbr=on}}, or 35% of the total river basin.<ref name="Bismarckdischarge">{{cite web
|url=http://wdr.water.usgs.gov/wy2010/pdfs/06342500.2010.pdf
|title=USGS Gage #06342500 on the Missouri River at Bismarck, ND
|publisher=U.S. Geological Survey
|work=National Water Information System
|date=1954–2010
|accessdate=2012-01-09}}</ref> At Kansas City, {{convert|366.1|mi|km}} from the mouth, the river's average flow is {{convert|55400|cuft/s|m3/s|abbr=on}}. The river here drains about {{convert|484100|mi2|km2|abbr=on}}, representing about 91% of the entire basin.<ref name="KSCdischarge">{{cite web
|url=http://wdr.water.usgs.gov/wy2010/pdfs/06893000.2010.pdf
|title=USGS Gage #06893000 on the Missouri River at Kansas City, MO
|publisher=U.S. Geological Survey
|work=National Water Information System
|date=1958–2010
|accessdate=2012-01-09}}</ref>

The lowermost gage with a period of record greater than fifty years is at [[Hermann, Missouri]] – {{convert|97.9|mi|km}} upstream of the mouth of the Missouri – where the average annual flow was {{convert|87520|cuft/s|m3/s|abbr=on}} from 1897 to 2010. About {{convert|522500|mi2|km2|abbr=on}}, or 98.7% of the watershed, lies above Hermann.<ref name="missouriflow"/> The highest annual mean was {{convert|181800|cuft/s|m3/s|abbr=on}} in 1993, and the lowest was {{convert|41690|cuft/s|m3/s|abbr=on}} in 2006.<ref name="missouriflow"/> Extremes of the flow vary even further. The largest discharge ever recorded was over {{convert|750000|cuft/s|m3/s|abbr=on}} on July 31, 1993, during [[Great Flood of 1993|a historic flood]].<ref>{{cite web|url=http://nwis.waterdata.usgs.gov/nwis/peak?site_no=06934500&agency_cd=USGS&format=html|title=USGS Gage #07010000 on the Mississippi River at St. Louis, Missouri: Peak Streamflow|publisher=U.S. Geological Survey|work=National Water Information System|date=1844–2009|accessdate=2010-08-24}}</ref> The lowest, a mere {{convert|602|cuft/s|m3/s|abbr=on}} – caused by the formation of an [[ice dam]] – was measured on December 23, 1963.<ref name="missouriflow"/>

==Geology==
[[File:Missouri-Mississippi confluence.jpg|thumb|upright|High [[silt]] content makes the Missouri River (left) noticeably lighter than the [[Mississippi River]] (right) at their confluence north of [[St. Louis, Missouri|St. Louis]].|alt=Top down view of two rivers merging, one dark and clear and the other light with clouds of sediment]]

The Rocky Mountains of southwestern Montana at the [[headwaters]] of the Missouri River first rose in the [[Laramide Orogeny]], a [[Mountain formation|mountain-building]] episode that occurred from around 70 to 45&nbsp;million years ago (the end of the [[Mesozoic]] through the early [[Cenozoic]]).<ref name="cenozoic map">{{cite web|last=Jones|first=Craig H.|title=Photo map of the western United States: Cenozoic|url=http://www.colorado.edu/GeolSci/Resources/WUSTectonics/PhotoMap.html|work=Western US Tectonics|publisher=University of Colorado|accessdate=2011-02-12}}</ref> This [[orogeny]] [[Tectonic uplift|uplifted]] [[Cretaceous]] rocks along the western side of the [[Western Interior Seaway]], a vast shallow sea that stretched from the Arctic Ocean to the Gulf of Mexico, and deposited the sediments that now underlie much of the drainage basin of the Missouri River.<ref>{{cite web
|url=http://jan.ucc.nau.edu/~rcb7/crepaleo.html
|title=Cretaceous Paleogeography, Southwestern US
|publisher=Northern Arizona University
|accessdate=2010-10-01}}</ref><ref>{{cite article
|last=Nicholls
|first=Elizabeth L.
|last1=Russell
|first1=Anthony P.
|title=Paleobiogeography of the Cretaceous Western Interior Seaway: the vertebrate evidence
|publisher=University of Calgary
|work=Department of Biological Sciences
|date=1989-09-18
|accessdate=2011-02-12}}</ref><ref>King, P. B., pp. 27–28</ref>
This Laramide uplift caused the sea to retreat and laid the framework for a vast drainage system of rivers flowing from the Rocky and [[Appalachian Mountains]], the predecessor of the modern-day Mississippi watershed.<ref>King, P. B., pp. 130–131</ref><ref>Baldridge, pp. 190–204</ref><ref>Roberts and Hodsdon, pp. 113–116</ref> The Laramide Orogeny is essential to modern Missouri River [[hydrology]], as snow and ice melt from the Rockies provide the majority of the flow in the Missouri and its tributaries.<ref>Benke and Cushing, p. 434</ref>

The Missouri and many of its tributaries cross the Great Plains, flowing over or cutting into the [[Ogallala Aquifer|Ogallala Group]] and older mid-Cenozoic sedimentary rocks. The lowest major Cenozoic unit, the [[White River Formation]], was deposited between roughly 35 and 29&nbsp;million years ago<ref name=laramide_cliamte>{{cite article
|author=Chapin, Charles E.
|title=Interplay of oceanographic and paleoclimate events with tectonism during middle to late Miocene sedimentation across the southwestern USA
|work=Geosphere (2008), 4(6):976
|url=http://mr.crossref.org/iPage/?doi=10.1130%2FGES00171.1
|accessdate=2011-01-20}}</ref><ref name=wyoming_white_river>{{cite web|author=Love, J.D.; Christiansen, Ann Coe|title=White River Formation|url=http://tin.er.usgs.gov/geology/state/sgmc-unit.php?unit=WYTwr;0|work=Mineral Resources On-Line Spatial Data|publisher=U.S. Geological Survey|accessdate=2011-02-12}}</ref> and consists of [[claystone]], [[sandstone]], [[limestone]], and [[Conglomerate (geology)|conglomerate]].<ref name=wyoming_white_river/><ref>{{cite web|author=Denson, N.M.; Gill, J.R.; Roberts, A.E.|title=White River Formation|url=http://tin.er.usgs.gov/geology/state/sgmc-unit.php?unit=MTTwr;0|work=Mineral Resources On-Line Spatial Data|publisher=U.S. Geological Survey|accessdate=2011-02-12}}</ref> Channel sandstones and finer-grained [[overbank deposit]]s of the [[fluvial]]<ref name="gs_arikaree">{{cite web|author=Martin, J. E.; Sawyer, J. F.; Fahrenbach, M. D.; Tomhave, D. W.; Schulz, L. D.|title=Arikaree Group|url=http://tin.er.usgs.gov/geology/state/sgmc-unit.php?unit=SDTa;0|work=Mineral Resources On-Line Spatial Data|publisher=U.S. Geological Survey|accessdate=2011-02-12}}</ref>  [[Arikaree Group]] were deposited between 29 and 19&nbsp;million years ago.<ref name=laramide_cliamte/> The [[Miocene]]-age Ogallala and the slightly younger [[Pliocene]]-age Broadwater Formation deposited atop the Arikaree Group, and are formed from material eroded off of the Rocky Mountains during a time of increased generation of topographic relief;<ref name=laramide_cliamte/><ref>{{cite article
|author=McMillan, Margaret E.
|title=Postdepositional tilt of the Miocene-Pliocene Ogallala Group on the western Great Plains: Evidence of late Cenozoic uplift of the Rocky Mountains
|work=Geology (2002), 30(1):63
|url=http://mr.crossref.org/iPage/?doi=10.1130%2F0091-7613%282002%29030%3C0063%3APTOTMP%3E2.0.CO%3B2
|accessdate=2012-01-20}}</ref> these formations stretch from the Rocky Mountains nearly to the Iowa border and give the Great Plains much of their gentle but persistent eastward tilt, and also constitute a major aquifer.<ref>King, P. B., pp. 128–130</ref>

Immediately before the [[Quaternary]] [[Ice Age]], the Missouri River was likely split into three segments: an upper portion that drained northwards into Hudson Bay,<ref>{{cite web
|last=Moak
|first=William
|url=http://maps.unomaha.edu/maher/2003mbfieldtrip/moakreport/pleistgeo.html
|title=Pleistocene Glaciation and Diversion of the Missouri River in Northern Montana
|publisher=University of Nebraska, Omaha
|work=Department of Geography and Geology
|accessdate=2010-10-01}}</ref><ref>{{cite web
|url=http://www3.northern.edu/natsource/HABITATS/Missio1.htm
|title=Missouri River
|publisher=Northern State University
|accessdate=2010-10-12}}</ref>
and middle and lower sections that flowed eastward down the regional slope.<ref>Thornbury, 1965, pp. 248–249, 295–296</ref>
As the Earth plunged into the Ice Age, a [[pre-Illinoian]] (or possibly the [[Illinoian]]) [[Glacial period|glaciation]] diverted the Missouri River southeastwards towards its present confluence with the Mississippi and caused it to integrate into a single river system that cuts across the regional slope.<ref>Thornbury, 1965, pp. 248–249, and references therein</ref> In western Montana, the Missouri River is thought to have once flowed north then east around the [[Bear Paw Mountains]]. [[Sapphire]]s are found in some spots along the river in western Montana.<ref name=gemgallerymtloc>{{cite web|title=Montana Sapphires – Gemology|url=http://www.gemgallery.com/#montana_sapphire_gemology|publisher=Gem Gallery|accessdate=2011-10-29}} Note: Includes map of major Montana sapphire mines</ref><ref>{{cite book |last=Voynick|first=Stephen M.|title=Yogo The Great American Sapphire|url=|publisher=Mountain Press Publishing|year=1985|edition=March 1995 printing, 1987|place=Missoula, MT|isbn=0-87842-217-X|page=193}}</ref> Advances of the continental ice sheets diverted the river and its tributaries, causing them to pool up into large temporary lakes such as Glacial Lakes [[Glacial Lake Great Falls|Great Falls]], [[Glacial Lake Musselshell|Musselshell]] and others. As the lakes rose, the water in them often spilled across adjacent local drainage divides, creating now-abandoned channels and [[coulee]]s including the [[Shonkin Sag]], {{convert|100|mi|km}} long. When the glaciers retreated, the Missouri flowed in a new course along the south side of the Bearpaws, and the lower part of the Milk River tributary took over the original main channel.<ref>{{cite web
|author=Moak, William
|url=http://maps.unomaha.edu/maher/2003mbfieldtrip/moakreport/pleistgeo.html
|title=Pleistocene Glaciation and Diversion of the Missouri River in Northern Montana
|publisher=University of Nebraska, Omaha
|work=Department of Geography and Geology
|accessdate=2011-06-28}}</ref>

The Missouri's nickname, the "Big Muddy", was inspired by its enormous loads of [[sediment]] or silt – some of the largest of any North American river.<ref name="Spotlight"/><ref>Benke and Cushing, pp. 432–434</ref> In its pre-development state, the river [[Sediment transport|transported]] some 175–320&nbsp;million short tons (193–290&nbsp;million t) per year.<ref>{{cite web
|url=http://www.mostreamteam.org/Documents/Research/BigRiver/MissouriRiverSediment.pdf
|title=Missouri River Sediment
|publisher=Missouri River Stream Team Website
|work=Missouri River Recovery Plan Fact Sheet, U.S. Army Corps of Engineers
|accessdate=2010-10-06}}</ref> The construction of dams and levees has drastically reduced this to 20–25&nbsp;million short tons (18–23&nbsp;million t) in the present day.<ref name="sediment-management"/> Much of this sediment is derived from the river’s [[floodplain]], also called the meander belt; every time the river changed course, it would erode tons of soil and rocks from its banks. However, damming and channeling the river has kept it from reaching its natural sediment sources along most of its course. Reservoirs along the Missouri trap roughly 36.4&nbsp;million short tons (32.9&nbsp;million t) of sediment each year.<ref name="MainstemSystem"/> Despite this, the river still transports more than half the total silt that empties into the Gulf of Mexico; the [[Mississippi River Delta]], formed by sediment deposits at the mouth of the Mississippi, constitutes a majority of sediments carried by the Missouri.<ref name="sediment-management">{{cite web
|url=http://dels.nas.edu/Report/Missouri-River-Planning-Recognizing-Incorporating/13019
|title=Missouri River Planning: Recognizing and Incorporating Sediment Management (2010)
|publisher=The National Academies
|work=Division on Earth and Life Studies
|accessdate=2010-10-07}}</ref><ref>{{cite news
|last=Schliefstein
|first=Mark
|url=http://www.nola.com/politics/index.ssf/2010/09/missouri_river_helped_build_lo.html
|title=Missouri River helped build Louisiana coast, but it won't help restore it
|publisher=New Orleans Net
|date=2010-09-29
|accessdate=2010-10-06}}</ref>

==First peoples==
{{See also|Plains Indians}}
Archaeological evidence, especially in Missouri, suggests that man first made his presence in the watershed of the Missouri River between 10,000 and 12,000 years ago at the end of the [[Pleistocene]].<ref name="archaeology">{{cite book
|last=Wedel
|first=Waldo Rudolph
|title=Prehistoric man on the Great Plains
|publisher=University of Oklahoma Press
|year=1961}}</ref> During the end of the [[last glacial period]], a great migration of humans began, traveling via the [[Beringia|Bering land bridge]] from Eurasia into and throughout the Americas. As they traveled slowly over centuries, the Missouri River formed one of the main migration paths. Most settled in the [[Ohio Valley]] and the lower Mississippi River Valley, but many, including the [[Mound builder (people)|Mound builders]], stayed along the Missouri, becoming the ancestors of the later indigenous peoples of the Great Plains.<ref>{{cite web
|url=http://www.nps.gov/history/seac/benning-book/ch01.htm
|title=Days of Giants and Ice
|publisher=U.S. National Park Service
|accessdate=2010-10-04}}</ref>

[[Image:A Mandan village 0049v cropped.jpg|thumb|left|Painting showing a village on a bluff above a river|[[Karl Bodmer]], ''A Mandan Village'', c. 1840–1843]]
The Native Americans that lived along the Missouri had access to ample food, water, and shelter. Many migratory animals inhabited the plains at the time, providing them meat, clothing, and other everyday items; there were also great [[Riparian zone|riparian]] areas in the river's floodplain that provided them with natural herbs and staple foods.<ref>{{cite web
|url=http://www.nps.gov/history/seac/benning-book/ch02.htm
|title=Stories Rocks Tell
|publisher=U.S. National Park Service
|accessdate=2010-10-04}}</ref> No written records from the tribes and peoples of the pre-European period exist because they did not use writing. According to the writings of explorers, some of the major tribes along the Missouri River included the [[Otoe tribe|Otoe]], [[Missouria]], [[Omaha (tribe)|Omaha]], [[Ponca]], [[Brulé]], [[Lakota people|Lakota]], [[Sioux]], [[Arikara]], [[Hidatsa]], [[Mandan]], [[Assiniboine people|Assiniboine]], [[Gros Ventres]] and [[Blackfeet]].<ref>Benke and Cushing, p. 432</ref>

Natives used the Missouri, at least to a limited extent, as a path of trade and transport. In addition, the river and its tributaries formed tribal boundaries. Lifestyles of the indigenous mostly centered around a semi-nomadic culture; many tribes would have different summer and winter camps. However, the center of Native American wealth and trade lay along the Missouri River in the Dakotas region on its great bend south.<ref>{{cite web
|url=http://www.nationalgeographic.com/lewisandclark/record_tribes_010_5_3.html
|title=Mandan Indians
|publisher=National Geographic
|work=Lewis and Clark Interactive Journey Log
|accessdate=2010-10-05}}</ref> A large cluster of walled Mandan, Hidatsa and Arikara villages situated on bluffs and islands of the river was home to thousands, and later served as a market and trading post used by early French and British explorers and fur traders.<ref>{{cite web
|url=http://www.nps.gov/archive/knri/overview.htm
|title=Knife River Indian Villages NHS
|publisher=U.S. National Park Service
|archiveurl=http://web.archive.org/web/20101129154050/http://www.nps.gov/archive/knri/overview.htm
|archivedate=2010-11-29
|accessdate=2010-10-05}}</ref> Following the introduction of horses to Missouri River tribes, possibly from feral European-introduced populations, natives' way of life changed dramatically. The use of the horse allowed them to travel greater distances, and thus facilitated hunting, communications and trade.<ref>Edwards, p. 123</ref>

Once, tens of millions of [[American bison]] (commonly called buffalo), one of the [[keystone species]] of the Great Plains and the Ohio Valley, roamed the plains of the Missouri River basin.<ref>Lott and Greene, p. 167</ref> Most Native American groups in the basin relied heavily on the bison as a food source, and their hides and bones served to create other household items. In time, the species came to benefit from the indigenous peoples' periodic controlled burnings of the grasslands surrounding the Missouri to clear out old and dead growth. The large bison population of the region gave rise to the term ''[[great bison belt]]'', an area of rich annual grasslands that extended from [[Alaska]] to Mexico along the eastern flank of the Continental Divide.<ref>Feldhamer, Thompson and Chapman, p. 1012</ref> However, after the arrival of Europeans in North America, both the bison and the Native Americans saw a rapid decline in population.<ref>{{cite web
|url=http://www.pbs.org/wnet/nature/episodes/american-buffalo-spirit-of-a-nation/introduction/2183/
|title=American Buffalo: Spirit of a Nation
|publisher=PBS Nature
|accessdate=2010-10-04}}</ref> Hunting eliminated bison populations east of the Mississippi River by 1833 and reduced the numbers in the Missouri basin to a mere few hundred. Foreign diseases such as [[smallpox]] raged across the land, decimating Native American populations. Left without their primary source of sustenance, many of the remaining indigenous people were amalgamated into resettlement areas and reservations.<ref>Lott and Greene, p. 171</ref>

==Early explorers==
[[File:PawneeVillasur1720.jpg|thumb|Massacre of the Villasur Expedition, painted c. 1720|alt=Painting of a group of Native Americans surrounding and fighting with explorers]]
In May 1673, the French explorers [[Louis Jolliet]] and [[Jacques Marquette]] left the settlement of [[St. Ignace, Michigan|St. Ignace]] on Lake Huron and traveled down the [[Wisconsin River|Wisconsin]] and Mississippi Rivers, aiming to reach the Pacific Ocean. In late June, Jolliet and Marquette became the first documented European discoverers of the Missouri River, which according to their journals was in full flood.<ref>{{cite web
|url=http://www.wisconsinhistory.org/diary/001412.asp
|title=Aug. 14, 1673: Passing the Missouri
|publisher=Wisconsin Historical Society
|work=Historic Diaries: Marquette and Joliet
|accessdate=2010-11-19}}</ref> "I never saw anything more terrific," Jolliet wrote, "a tangle of entire trees from the mouth of the Pekistanoui [Missouri] with such impetuosity that one could not attempt to cross it without great danger. The commotion was such that the water was made muddy by it and could not clear itself."<ref name="Houck">Houck, pp. 160–161</ref><ref>Kellogg, p. 249</ref> They recorded ''Pekitanoui'' or ''Pekistanoui'' as the local name for the Missouri. However, the party never explored the Missouri beyond its mouth, nor did they linger in the area. In addition, they later learned that the Mississippi drained into the Gulf of Mexico and not the Pacific as they had originally presumed; the expedition turned back about {{convert|440|mi|km}} short of the Gulf at the confluence of the Arkansas River with the Mississippi.<ref name="Houck"/>

In 1682, France expanded its territorial claims in North America to include land on the western side of the Mississippi River, which included the lower portion of the Missouri. However, the Missouri itself remained formally unexplored until [[Étienne de Veniard, Sieur de Bourgmont]] commanded an expedition in 1714 that reached at least as far as the mouth of the Platte River. It is unclear exactly how far Bourgmont traveled beyond there; he described the blond-haired [[Mandan]]s in his journals, so it is likely he reached as far as their villages in present-day North Dakota.<ref>{{cite article
|editor=Blackmar, Frank W.
|title=Bourgmont’s Expedition
|work=Kansas: a cyclopedia of state history, embracing events, institutions, industries, counties, cities, towns, prominent persons, etc.
|year=1912}}</ref> Later that year, Bourgmont published ''The Route To Be Taken To Ascend The Missouri River'', the first known document to use the name "Missouri River"; many of the names he gave to tributaries, mostly for the native tribes that lived along them, are still in use today. The expedition's discoveries eventually found their way to cartographer [[Guillaume Delisle]], who used the information to create a map of the lower Missouri.<ref name="Bourgmont">{{cite web
|last=Hechenberger
|first=Dan
|url=http://www.nps.gov/jeff/historyculture/loader.cfm?csModule=security/getfile&pageid=145929
|title=Etienne de Véniard sieur de Bourgmont: timeline
|publisher=U.S. National Park Service
|accessdate=2011-01-07}}</ref> In 1718, [[Jean-Baptiste Le Moyne, Sieur de Bienville]] requested that the French government bestow upon Bourgmont the [[Order of Saint Louis|Cross of St. Louis]] because of his "outstanding service to France".<ref name="Bourgmont"/>

Bourgmont had in fact been in trouble with the French colonial authorities since 1706, when he deserted his post as commandant of [[Fort Detroit]] after poorly handling an [[Siege of Fort Detroit|attack]] by the [[Ottawa (tribe)|Ottawa]] that resulted in thirty-one deaths.<ref>{{cite web
|last=Nolan
|first=Jenny
|url=http://apps.detnews.com/apps/history/index.php?id=180
|title=Chief Pontiac's siege of Detroit
|publisher=Detroit News
|work=Michigan History
|date=2000-06-14
|accessdate=2010-10-04}}</ref> However, his reputation was enhanced in 1720 when the [[Pawnee people|Pawnee]] – who had earlier been befriended by Bourgmont – massacred the Spanish [[Villasur expedition]] near present-day [[Columbus, Nebraska]] on the Missouri River and temporarily ending Spanish encroachment on French Louisiana.<ref>{{cite web
|url=http://www.nebraskahistory.org/publish/markers/texts/villasur_expedition_1720.htm
|title=The Villasur Expedition–1720
|publisher=Nebraska State Historical Society
|date=2004-06-04
|accessdate=2012-01-19}}</ref> 

Bourgmont established [[Fort Orleans]], the first European settlement of any kind on the Missouri River, near present-day [[Brunswick, Missouri]], in 1723. The following year Bourgmont led an expedition to enlist [[Comanche]] support against the Spanish, who continued to show interest in taking over the Missouri. In 1725 Bourgmont brought the chiefs of several Missouri River tribes to visit France. There he was raised to the rank of nobility and did not accompany the chiefs back to North America. Fort Orleans was either abandoned or its small contingent massacred by Native Americans in 1726.<ref name="Bourgmont"/><ref>Houck, pp. 258–265</ref>

The [[French and Indian War]] erupted when territorial disputes between France and Great Britain in North America reached a head in 1754. By 1763, France was defeated by the much greater strength of the British army and was forced to cede its Canadian possessions to the English and Louisiana to the Spanish in the [[Treaty of Paris (1763)|Treaty of Paris]], amounting to most of its colonial holdings in North America.<ref>{{cite web
|url= http://avalon.law.yale.edu/18th_century/paris763.asp
|title= The definitive Treaty of Peace and Friendship between his Britannick Majesty, the Most Christian King, and the King of Spain. Concluded at Paris the 10th day of February, 1763. To which the King of Portugal acceded on the same day. (Printed from the Copy.)
|publisher=Yale Law School
|work=The Avalon Project
|accessdate=2010-10-05}}</ref> Initially, the Spanish did not extensively explore the Missouri and let French traders continue their activities under license. However, this ended after news of the British [[Hudson's Bay Company]] incursions in the upper Missouri River watershed was brought back following an expedition by Jacques D'Eglise in the early 1790s.<ref>{{cite article
|last=Nasatir
|first=Abraham P.
|title=Jacques d’Eglise on the Upper Missouri, 1791–1795
|work=Mississippi Valley Historical Review
|pages=47–56
|year=1927
|accessdate=2012-01-19}}</ref> In 1795 the Spanish chartered the Company of Discoverers and Explorers of the Missouri, popularly referred to as the "Missouri Company", and offered a reward for the first person to reach the Pacific Ocean via the Missouri. In 1794 and 1795 expeditions led by Jean Baptiste Truteau and Antoine Simon Lecuyer de la Jonchšre did not even make it as far north as the Mandan villages in central North Dakota.<ref name="Evans">{{cite article
|last=Williams
|first=David
|title=John Evans’ Strange Journey: Part II. Following the Trail
|work=American Historical Review
|year=1949
|pages=508–529
|accessdate=2012-01-19}}</ref>

Arguably the most successful of the Missouri Company expeditions was that of James MacKay and [[John Evans (explorer)|John Evans]].<ref>{{cite web
|url=http://www.museum.state.il.us/exhibits/lewis_clark_il/htmls/il_country_exp/preps/mackay_evans_map.html
|title=The Mackay and Evans Map
|publisher=Illinois State Museum
|work=Lewis and Clark in the Illinois Country
|accessdate=2012-01-23}}</ref> The two set out along the Missouri, and established Fort Charles about {{convert|20|mi|km}} south of present-day Sioux City as a winter camp in 1795. At the Mandan villages in North Dakota, they expelled several British traders, and while talking to the populace they pinpointed the location of the Yellowstone River, which was called ''Roche Jaune'' ("Yellow Rock") by the French. Although MacKay and Evans failed to accomplish their original goal of reaching the Pacific, they did create the first accurate map of the upper Missouri River.<ref name="Evans"/><ref>{{cite web
|last=Witte
|first=Kevin C.
|url= http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1132&context=greatplainsquarterly
|title= In the Footsteps of the Third Spanish Expedition: James Mackay and John T. Evans' Impact on the Lewis and Clark Expedition
|publisher=University of Nebraska – Lincoln
|work=Great Plains Studies, ''Center for Great Plains Quarterly''
|year=2006
|accessdate=2010-10-05}}</ref>

In 1795, the young United States and Spain signed [[Pinckney's Treaty]], which recognized American rights to navigate the Mississippi River and store goods for export in New Orleans.<ref>{{cite web
|url=http://www.uv.es/EBRIT/micro/micro_468_15.html
|title=Pinckney's Treaty or Treaty of San Lorenzo
|publisher=Encyclopædia Britannica
|accessdate=2010-10-04}} {{Dead link|date=April 2012|bot=H3llBot}}</ref> Three years later, Spain revoked the treaty and in 1800 secretly returned Louisiana to [[Napoleon Bonaparte|Napoleon]]ic France in the [[Third Treaty of San Ildefonso]]. This transfer was so secret that the Spanish continued to administer the territory. In 1801, Spain restored rights to use the Mississippi and New Orleans to the United States.<ref>{{cite web
|url=http://www.napoleon-series.org/research/government/diplomatic/c_ildefonso.html
|title=Treaty of San Ildefonso
|publisher=The Napoleon Series
|work=Government & Politics
|accessdate=2010-10-04}}</ref>

[[File:Map of Lewis and Clark's Track, Across the Western Portion of North America, published 1814.jpg|thumb|left|300px|alt=An early map of western North America|Map of western North America drawn by [[Lewis and Clark Expedition|Lewis and Clark]]]]
Fearing that the cutoffs could occur again, President [[Thomas Jefferson]] proposed to buy the port of New Orleans from France for $10 million. Instead, faced with a debt crisis, Napoleon offered to sell the entirety of Louisiana, including the Missouri River, for $15 million – amounting to less than 3¢ per acre. The deal was signed in 1803, doubling the size of the United States with the acquisition of the [[Louisiana Territory]].<ref>{{cite web
|url=http://www.nps.gov/archive/jeff/lewisclark2/circa1804/heritage/louisianapurchase/louisianapurchase.htm
|title=Louisiana Purchase
|publisher=U.S. National Park Service
|work=The Lewis and Clark Journey of Discovery
|archiveurl=http://web.archive.org/web/20101129154059/http://www.nps.gov/archive/jeff/lewisclark2/circa1804/heritage/louisianapurchase/louisianapurchase.htm
|archivedate=2010-11-29
|accessdate=2010-10-04}}</ref> In 1803, Jefferson instructed [[Meriwether Lewis]] to explore the Missouri and search for a water route to the Pacific Ocean. By then, it had been discovered that the Columbia River system, which drains into the Pacific, had a similar latitude as the headwaters of the Missouri River, and it was widely believed that a connection or short portage existed between the two.<ref name="lewis1">{{cite web
|title = Jefferson's Instructions for Meriwether Lewis
|url = http://www.loc.gov/exhibits/lewisandclark/lewis-landc.html#57
|publisher=U.S. Library of Congress
|accessdate = 2006-06-30}}</ref> However, Spain balked at the takeover, citing that they had never formally returned Louisiana to the French. Spanish authorities warned Lewis not to take the journey and forbade him from seeing the MacKay and Evans map of the Missouri, although Lewis eventually managed to gain access to it.<ref>{{cite web
|url=http://www.museum.state.il.us/exhibits/lewis_clark_il/htmls/il_country_exp/preps/mackay_evans_map.html
|title=The Mackay and Evans Map
|publisher=The Illinois State Museum
|work=Lewis and Clark in the Illinois Country
|accessdate=2011-01-06}}</ref><ref>{{cite web
|url=http://www2.lib.virginia.edu/exhibits/lewis_clark/exploring/ch4.html
|title=To the Western Ocean: Planning the Lewis and Clark Expedition
|publisher=University of Virginia Library
|work=Exploring the West from Monticello: A Perspective in Maps from Columbus to Lewis and Clark
|accessdate=2011-01-06}}</ref>

Meriwether Lewis and [[William Clark (explorer)|William Clark]] began [[Lewis and Clark Expedition|their famed expedition]] in 1804 with a party of thirty-three people in three boats.<ref name="L&C2">{{cite web
|url=http://www.nationalgeographic.com/lewisandclark/journey_leg_1.html
|title=The Journey Begins
|publisher=National Geographic
|work=Lewis & Clark Interactive Journey Log
|accessdate=2010-10-05}}</ref> Although they became the first Europeans to travel the entire length of the Missouri and reach the Pacific Ocean via the Columbia, they found no trace of the Northwest Passage. The maps made by Lewis and Clark, especially those of the [[Pacific Northwest]] region, provided a foundation for future explorers and emigrants. They also negotiated relations with multiple Native American tribes and wrote extensive reports on the climate, ecology and geology of the region. Many present-day names of geographic features in the upper Missouri basin originated from their expedition.<ref>{{cite web
|url=http://www.nps.gov/nr/travel/lewisandclark/intro.htm
|title=Introduction
|publisher=U.S. National Park Service
|work=Lewis and Clark Expedition: A National Register of Historic Places Travel Itinerary
|accessdate=2010-10-05}}</ref>

==American frontier==

===Fur trade===
[[File:George Caleb Bingham 001.jpg|thumb|right|''Fur Traders on Missouri River'', painted by [[George Caleb Bingham]] c. 1845|alt=Painting of two figures and a cat on a boat in a placid body of water]]
As early as the 18th century, fur trappers entered the extreme northern basin of the Missouri River in the hopes of finding populations of [[North American Beaver|beaver]] and [[North American River Otter|river otter]], the sale of whose pelts drove the thriving [[North American fur trade]]. They came from many different places – some from the Canadian fur corporations at Hudson Bay, some from the Pacific Northwest (see also [[Maritime Fur Trade]]), and some from the midwestern United States. Most did not stay in the area for long, as they failed to find significant resources.<ref>{{cite web
|url=http://lewis-clark.org/content/content-article.asp?ArticleID=2970
|title=Manuel Lisa's Fort Raymond: First Post in the Far West
|publisher=The Lewis and Clark Fort Mandan Foundation
|work=Discovering Lewis and Clark
|accessdate=2010-10-18}}</ref>

The first glowing reports of country rich with thousands of game animals came in 1806 when Meriwether Lewis and William Clark returned from their two-year expedition. Their journals described lands rich with thousands of buffalo, beaver, and river otter; and also an abundant population of [[sea otter]]s on the Pacific Northwest coast. In 1807, explorer [[Manuel Lisa]] organized an expedition which would lead to the explosive growth of the fur trade in the upper Missouri River country. Lisa and his crew traveled up the Missouri and Yellowstone Rivers, trading manufactured items in return for furs from local Native American tribes, and established a fort at the confluence of the Yellowstone and a tributary, the [[Bighorn River|Bighorn]], in southern Montana. Although the business started small, it quickly grew into a thriving trade.<ref>{{cite web
|url=http://www.history.com/this-day-in-history/fur-trader-manuel-lisa-dies
|title=Fur trader Manuel Lisa dies
|publisher=A&E Television Networks
|work=This Day in History
|accessdate=2010-10-18}}</ref><ref>{{cite web
|url=http://lewis-clark.org/content/content-article.asp?ArticleID=2868
|title=Post-Expedition Fur Trade: "The Great Engine"
|publisher=The Lewis and Clark Fort Mandan Foundation
|work=Discovering Lewis and Clark
|accessdate=2010-10-19}}</ref>

Lisa's men started construction of [[Fort Raymond]], which sat on a bluff overlooking the confluence of the Yellowstone and Bighorn, in the fall of 1807. The fort would serve primarily as a trading post for bartering with the Native Americans for furs.<ref>Morris, pp. 40–41</ref> This method was unlike that of the Pacific Northwest fur trade, which involved trappers hired by the various fur enterprises, namely [[Hudson's Bay Company|Hudson's Bay]]. Fort Raymond was later replaced by [[Fort Lisa (North Dakota)|Fort Lisa]] at the confluence of the Missouri and Yellowstone in North Dakota; a second fort also called [[Fort Lisa (Nebraska)|Fort Lisa]] was built downstream on the Missouri River in Nebraska. In 1809 the [[St. Louis Missouri Fur Company]] was founded by Lisa in conjunction with William Clark and [[Pierre Choteau]], among others.<ref>South Dakota State Historical Society & South Dakota Department of History pp. 320–325</ref><ref name="npsfur">{{cite web
|url=http://www.nps.gov/history/nr/travel/pierre_fortpierre/early_exploration_fur_trade_essay.html
|title=Early Exploration and the Fur Trade
|publisher=U.S. National Park Service
|accessdate=2010-10-19}}</ref> In 1828, the [[American Fur Company]] founded [[Fort Union Trading Post National Historic Site|Fort Union]] at the confluence of the Missouri and Yellowstone Rivers. Fort Union gradually became the main headquarters for the fur trade in the upper Missouri basin.<ref>{{cite web
|url=http://www.nps.gov/nr/travel/lewisandclark/uni.htm
|title=Fort Union Trading Post National Historic Site
|publisher=U.S. National Park Service
|work=Lewis & Clark Expedition
|accessdate=2012-02-11}}</ref>

Fur trapping activities in the early 19th century encompassed nearly all of the Rocky Mountains on both the eastern and western slopes. Trappers of the Hudson's Bay Company, St. Louis Missouri Fur Company, American Fur Company, [[Rocky Mountain Fur Company]], [[North West Company]] and other outfits worked thousands of streams in the Missouri watershed as well as the neighboring Columbia, Colorado, Arkansas, and Saskatchewan river systems. During this period, the trappers, also called [[Mountain man|mountain men]], blazed trails through the wilderness that would later form the paths pioneers and settlers would travel by into the West. Transport of the thousands of beaver pelts required ships, providing one of the first large motives for river transport on the Missouri to start.<ref>Sunder, p. 10</ref>

As the 1830s drew to a close, the fur industry slowly began to die as silk replaced beaver fur as a desirable clothing item. By this time, also, the beaver population of streams in the Rocky Mountains had been decimated by intense hunting. Furthermore, frequent Native American attacks on trading posts made it dangerous for employees of the fur companies. In some regions, the industry continued well into the 1840s, but in others such as the Platte River valley, declines of the beaver population contributed to an earlier demise.<ref>Sunder, p. 8</ref> The fur trade finally disappeared in the Great Plains around 1850, with the primary center of industry shifting to the Mississippi Valley and central Canada. Despite the demise of the once-prosperous trade, however, its legacy led to the opening of the American West and a flood of settlers, farmers, ranchers, adventurers, hopefuls, financially bereft, and entrepreneurs took their place.<ref>Sunder, pp. 12–15</ref>

===Settlers and pioneers===
{{see also|Department of the Missouri|American Indian Wars}}
[[File:George Caleb Bingham - Boatmen on the Missouri - Google Art Project.jpg|thumb|''Boatmen on the Missouri'' c. 1846]]
The river roughly defined the [[Frontier#American frontier|American frontier]] in the 19th century, particularly downstream from Kansas City, where it takes a sharp eastern turn into the heart of the state of Missouri. The major trails for the opening of the American West all have their starting points on the river, including the [[California Trail|California]], [[Mormon Trail|Mormon]], [[Oregon Trail|Oregon]], and [[Santa Fe Trail|Santa Fe]] trails. The first westward leg of the [[Pony Express]] was a ferry across the Missouri at [[St. Joseph, Missouri]]. Similarly, most emigrants arrived at the eastern terminus of the [[First Transcontinental Railroad]] via a ferry ride across the Missouri between [[Council Bluffs, Iowa]] and Omaha.<ref>Dick, pp. 127–132</ref><ref>{{cite web
|url=http://www.history.com/topics/transcontinental-railroad
|title=The Transcontinental Railroad
|publisher=History Channel
|work=History.com
|accessdate=2010-10-07}}</ref> The [[Hannibal Bridge]] became the first bridge to cross the Missouri River in 1869, and its location was a major reason why Kansas City became the largest city on the river upstream from its mouth at St. Louis.<ref>{{cite web
|url=http://www.kclibrary.org/?q=blog/week-kansas-city-history/bridge-future
|title=Bridge to the Future
|publisher=Kansas City Public Library
|date=2009-12-09
|accessdate=2010-10-07}}</ref> 

True to the then-ideal of [[Manifest Destiny]], over 500,000 people set out from the river town of [[Independence, Missouri]] to their various destinations in the American West from the 1830s to the 1860s. These people had many reasons to embark on this strenuous year-long journey – economic crisis, and later gold strikes including the [[California Gold Rush]], for example.<ref>{{cite web
|url=http://www.nebraskahistory.org/publish/publicat/books/ourbooks/mattes.htm
|title=The Great Platte River Road
|publisher=Nebraska State Historical Society
|date=1998-06-30
|accessdate=2011-01-07}}</ref> For most, the route took them up the Missouri to Omaha, Nebraska, where they would [[Great Platte River Road|set out along the Platte River]], which flows from the Rocky Mountains in Wyoming and Colorado eastwards through the Great Plains. An early expedition led by [[Robert Stuart (explorer)|Robert Stuart]] from 1812 to 1813 proved the Platte impossible to navigate by the [[dugout canoe]]s they used, let alone the large sidewheelers and sternwheelers that would later ply the Missouri in increasing numbers. One explorer remarked that the Platte was "too thick to drink, too thin to plow".<ref>Cech, p. 424</ref> Nevertheless, the Platte provided an abundant and reliable source of water for the pioneers as they headed west. Covered wagons, popularly referred to as ''prairie schooners'', provided the primary means of transport until the beginning of regular boat service on the river in the 1850s.<ref>Mattes, pp. 4–11</ref>

During the 1860s, gold strikes in Montana, Colorado, Wyoming and northern [[Utah]] attracted another wave of hopefuls to the region. Although some freight was hauled overland, most transport to and from the gold fields was done through the Missouri and Kansas Rivers, as well as the [[Snake River]] in western Wyoming and the [[Bear River (Utah)|Bear River]] in Utah, Idaho and Wyoming.<ref>Holmes, Walter and Dailey, pp. 105–106</ref> It is estimated that of the passengers and freight hauled from the Midwest to Montana, over 80&nbsp;percent were transported by boat, a journey that took 150 days in the upstream direction. A route more directly west into Colorado lay along the Kansas River and its tributary the Republican River as well as pair of smaller Colorado streams, [[Big Sandy Creek (Colorado)|Big Sandy Creek]] and the [[South Platte River]], to near Denver. The gold rushes precipitated the decline of the [[Bozeman Trail]] as a popular emigration route, as it passed through land held by often-hostile Native Americans. Safer paths were blazed to the [[Great Salt Lake]] near [[Corinne, Utah]] during the gold rush period, which led to the large-scale settlement of the Rocky Mountains region and eastern [[Great Basin]].<ref>Athearn, pp. 87–88</ref>

[[File:bodmer5455.jpg|thumb|left|180px|Karl Bodmer, ''[[Fort Pierre, South Dakota|Fort Pierre]] and the Adjacent Prairie'', c. 1833|alt=Painting of a fort surrounded by tepees on the bank of a river curving around a series of bluffs]]
As settlers expanded their holdings into the Great Plains, they ran into land conflicts with Native American tribes. This resulted in frequent raids, massacres and armed conflicts, leading to the federal government creating multiple treaties with the Plains tribes, which generally involved establishing borders and reserving lands for the indigenous. As with many other treaties between the U.S. and Native Americans, they were soon broken, leading to huge wars. Over 1,000 battles, big and small, were fought between the U.S. military and Native Americans before the tribes were forced out of their land onto reservations.<ref>{{cite web
|url=http://www.pbs.org/wgbh/americanexperience/features/interview/tcrr-interview/
|title=Native Americans
|publisher=PBS
|work=Transcontinental Railroad: The Film
|accessdate=2010-10-05}}</ref><ref>{{cite web
|url=http://www.history.army.mil/html/reference/army_flag/iw.html
|title=U.S. Army Campaigns: Indian Wars
|publisher=U.S. Army Center of Military History
|date=2009-08-03
|accessdate=2010-10-07}}</ref>

Conflicts between natives and settlers over the opening of the Bozeman Trail in the Dakotas, Wyoming and Montana led to [[Red Cloud's War]], in which the [[Lakota people|Lakota]] and [[Cheyenne]] fought against the U.S. Army. The fighting resulted in a complete Native American victory.<ref>{{cite article
|title=Red Cloud's War (United States history)
|publisher=Encyclopædia Britannica
|accessdate=2010-10-05
|url=http://www.britannica.com/EBchecked/topic/1563057/Red-Clouds-War}}</ref> In 1868, the [[Treaty of Fort Laramie (1868)|Treaty of Fort Laramie]] was signed, which "guaranteed" the use of the [[Black Hills]], [[Powder River Country]] and other regions surrounding the northern Missouri River to Native Americans without white intervention.<ref name="Laramie1868">{{cite web
|last=Clark
|first=Linda Darus
|url=http://www.archives.gov/education/lessons/sioux-treaty/
|title=Teaching with Documents: Sioux Treaty of 1868
|publisher=National Archives
|work=Expansion & Reform
|accessdate=2010-11-10}}</ref>The Missouri River was also a significant landmark as it divides northeastern Kansas from western Missouri; pro-slavery forces from Missouri would cross the river into Kansas and spark mayhem during [[Bleeding Kansas]], leading to continued tension and hostility even today between [[Kansas and Missouri]]. Another significant military engagement on the Missouri River during this period was the [[Battle of Boonville|1861 Battle of Boonville]], which did not affect Native Americans but rather was a turning point in the [[American Civil War]] that allowed the [[Union (American Civil War)|Union]] to seize control of transport on the river, discouraging the state of Missouri from joining the [[Confederate States of America|Confederacy]].<ref>{{cite web
|url=http://www.cr.nps.gov/hps/abpp/battles/mo001.htm
|title=Boonville
|publisher=U.S. National Park Service
|work=CWSAC Battle Summaries
|accessdate=2011-03-05}}</ref>

However, the peace and freedom of the Native Americans did not last for long. The [[Great Sioux War of 1876|Great Sioux War]] of 1876&ndash;77 was sparked when American miners discovered gold in the Black Hills of western South Dakota and eastern Wyoming. These lands were originally set aside for Native American use by the Treaty of Fort Laramie.<ref name="Laramie1868"/> When the settlers intruded onto the lands, they were attacked by Native Americans. U.S. troops were sent to the area to protect the miners, and drive out the natives from the new settlements. During this bloody period, both the Native Americans and the U.S. military won victories in major battles, resulting in the loss of nearly a thousand lives. The war eventually ended in an American victory, and the Black Hills were opened to settlement. Native Americans of that region were relocated to reservations in Wyoming and southeastern Montana.<ref>Greene, pp. xv–xxvi</ref>

==Dam-building era==
[[Image:HolterDam1918.jpg|thumb|alt=Front view of a dam releasing water through its spillways|[[Holter Dam]], a run-of-the-river structure on the upper Missouri, shortly after completion in 1918]]
{{Further2|[[List of dams in the Missouri River watershed]]}}
In the late 19th and early 20th centuries, a great number of dams were built along the course of the Missouri, transforming 35&nbsp;percent of the river into a chain of reservoirs.<ref name="Story"/> River development was stimulated by a variety of factors, first by growing demand for electricity in the rural northwestern parts of the basin, and also by floods and droughts that plagued rapidly growing agricultural and urban areas along the lower Missouri River.<ref name="Pick-Sloan"/> Small, privately owned hydroelectric projects have existed since the 1890s, but the large flood-control and storage dams that characterize the middle reaches of the river today were not constructed until the 1950s.<ref name="MainstemSystem"/><ref name="Pick-Sloan"/>

Between 1890 and 1940, five dams were built in the vicinity of [[Great Falls, Montana|Great Falls]] to generate power from the [[Great Falls of the Missouri]], a chain of giant waterfalls formed by the river in its path through western Montana. [[Black Eagle Dam]], built in 1891 on [[Black Eagle Falls]], was the first dam of the Missouri.<ref>''Montana: A State Guide Book'', p. 150</ref> Replaced in 1926 with a more modern structure, the dam was little more than a small weir atop Black Eagle Falls, diverting part of the Missouri's flow into the Black Eagle power plant.<ref name="BlackEagleDam">{{cite web
|url=http://www.pplmontana.com/producing+power/power+plants/Black+Eagle+Dam.htm
|title=Black Eagle Dam
|publisher=PPL Montana
|work=Producing Power
|accessdate=2010-10-07}}</ref> The largest of the five dams, [[Ryan Dam]], was built in 1913. The dam lies directly above the {{convert|87|ft|m|adj=on}} [[Great Falls (Missouri River waterfall)|Great Falls]], the largest waterfall of the Missouri.<ref name="RyanDam">{{cite web
|url=http://www.pplmontana.com/producing+power/power+plants/Ryan+Dam.htm
|title=Ryan Dam
|publisher=PPL Montana
|work=Producing Power
|accessdate=2010-10-08}}</ref>

[[Image:Black Eagle Dam 1908 DYK.jpg|thumb|right|170px|alt=View of an explosion atop a dam in a flooding river|Black Eagle Dam is dynamited in 1908 to save Great Falls from the floodwave caused by the failure of Hauser Dam]]
In the same period, several private establishments – most notably the [[Montana Power Company]] – began to develop the Missouri River above Great Falls and below [[Helena, Montana|Helena]] for power generation. A small [[Run-of-the-river hydroelectricity|run-of-the river]] structure completed in 1898 near the present site of [[Canyon Ferry Dam]] became the second dam to be built on the Missouri. This rock-filled [[Dam#Timber dams|timber crib dam]] generated seven and a half [[megawatt]]s of electricity for Helena and the surrounding countryside.<ref>Mulvaney, p. 112</ref> The nearby [[Steel dam|steel]] [[Hauser Dam]] was finished in 1907, but failed in 1908 because of structural deficiencies, causing catastrophic flooding all the way downstream past [[Craig, Montana|Craig]]. At Great Falls, a section of the Black Eagle Dam was dynamited to save nearby factories from inundation.<ref>Mulvaney, p. 39</ref> Hauser was rebuilt in 1910 as a concrete gravity structure, and stands to this day.<ref name="Hauser">{{cite web
|url=http://www.pplmontana.com/producing+power/power+plants/Hauser+Dam.htm
|title=Hauser Dam
|work=Producing Power
|publisher=PPL Montana
|accessdate=2010-12-02}}</ref><ref>{{cite web
|url=http://helenair.com/news/local/article_ab5ce658-c9e1-5ade-a9c4-8b371a5ceecf.html
|title=Original Hauser Dam fell to mighty Missouri
|last=Kline
|first=Larry
|publisher=Helena Independent Record
|date=2008-04-15
|accessdate=2010-12-02}}</ref> 

[[Holter Dam]], about {{convert|45|mi|km}} downstream of Helena, was the third hydroelectric dam built on this stretch of the Missouri River.<ref name="HolterDam">{{cite web
|url=http://www.pplmontana.com/producing+power/power+plants/Holter+Dam.htm
|title=Holter Dam
|publisher=PPL Montana
|work=Producing Power
|accessdate=2010-10-07}}</ref> When completed in 1918 by the Montana Power Company and the [[United Missouri River Power Company]], its reservoir flooded the [[Gates of the Mountains Wilderness|Gates of the Mountains]], a limestone canyon which Meriwether Lewis described as "the most remarkable clifts that we have yet seen… the tow[er]ing and projecting rocks in many places seem ready to tumble on us."<ref>{{cite web
|url=http://www.mbmg.mtech.edu/gmr/lewis_clark/lewis_clark-gates.asp
|title=Gates of the Mountains
|publisher=Montana Bureau of Mines and Geology
|work=Lewis and Clark–A Geologic Perspective
|accessdate=2012-01-16}}</ref> In 1949, the [[U.S. Bureau of Reclamation]] (USBR) began construction on the modern Canyon Ferry Dam to provide flood control to the Great Falls area. By 1954, the rising waters of [[Canyon Ferry Lake]] submerged the old 1898 dam, whose powerhouse still stands underwater about {{convert|1.5|mi|km}} upstream of the present-day dam.<ref name="CanyonFerryDam">{{cite web
|url=http://www.usbr.gov/projects/Facility.jsp?fac_Name=Canyon+Ferry+Dam&groupName=General
|title=Canyon Ferry Dam
|publisher=U.S. Bureau of Reclamation
|date=2010-08-10
|accessdate=2011-01-07}}</ref>

<blockquote class="toccolours" style="text-align:justify; width:30%; float:left; padding:10px 15px; display:table;">"[The Missouri's temperament was] uncertain as the actions of a jury or the state of a woman's mind." <br/><small>–''Sioux City Register'', March 28, 1868<ref name="RNA438"/></small></blockquote>

The Missouri basin suffered a series of catastrophic floods around the turn of the 20th century, most notably in [[Great Flood of 1844|1844]], [[Great Flood of 1881|1881]], and [[Great Mississippi Flood of 1927|1926–1927]].<ref name="flooding"/> In 1940, as part of the [[Great Depression]]-era [[New Deal]], the [[U.S. Army Corps of Engineers]] (USACE) completed Fort Peck Dam in Montana. Construction of this massive public works project provided jobs for more than 50,000 laborers during the Depression and was a major step in providing flood control to the lower half of the Missouri River.<ref>{{cite news
|author=Johnson, Marc
|url=http://www.newwest.net/topic/article/dam_politics_could_a_project_like_fort_peck_get_built_today/C37/L37/
|title=Dam Politics: Could a Project Like Fort Peck Get Built Today?
|work=New West Politics
|date=2011-05-20
|accessdate=2012-01-16}}</ref> However, Fort Peck only controls runoff from 11&nbsp;percent of the Missouri River watershed, and had little effect on a severe snowmelt flood that struck the lower basin three years later. This event was particularly destructive as it submerged manufacturing plants in Omaha and Kansas City, greatly delaying shipments of military supplies in World War II.<ref name="flooding">{{cite web
|url=http://www.dnr.state.ne.us/floodplain/mitigation/mofloods.html
|title=Historic Floods on the Missouri River: Fighting the Big Muddy in Nebraska
|publisher=Nebraska Department of Natural Resources
|accessdate=2010-10-05}}</ref><ref>{{cite web
|url=http://www.nwk.usace.army.mil/pa/History/timeline-1938-1947.pdf
|title=The Fourth Decade of the Kansas City District: 1938–1947
|publisher=U.S. Army Corps of Engineers
|accessdate=2012-01-19}}</ref>

[[File:Pick-Sloan Plan.png|thumb|left|alt=Map showing major dams and reservoirs in the Missouri River basin|Map showing major features of the [[Pick–Sloan Plan]]; other dams and their reservoirs are denoted by triangles]]
[[Image:Fort Peck Dam (Fort Peck Montana) 1986 01.jpg|thumb|left|alt=Aerial view of a large earthfill dam with its reservoir on the left and background, surrounded by brownish hills|[[Fort Peck Dam]], the uppermost dam of the Missouri River Mainstem System]]
Flooding damages on the Mississippi&ndash;Missouri river system were one of the primary reasons for which [[United States Congress|Congress]] passed the [[Flood Control Act of 1944]], opening the way for the USACE to develop the Missouri on a massive scale.<ref>{{cite web
|url=http://www.fws.gov/laws/lawsdigest/flood.html
|title=Flood Control Act of 1944
|publisher=U.S. Fish and Wildlife Service
|work=Digest of Federal Resource Laws of Interest to the U.S. Fish and Wildlife Service
|accessdate=2010-10-05}}</ref><ref>{{cite web
|url=http://www.msaconline.com/Missouri%20River%20Basin%20Project%20-%20The%20System.htm
|title=Missouri River Basin Project: The System
|publisher=Missouri Sediment Action Coalition
|year=2011
|accessdate=2012-03-10}}</ref> The 1944 act authorized the [[Pick–Sloan Missouri Basin Program]] (Pick–Sloan Plan), which was a composite of two widely varying proposals. The Pick plan, with an emphasis on flood control and hydroelectric power, called for the construction of large storage dams along the main stem of the Missouri. The Sloan plan, which stressed the development of local irrigation, included provisions for roughly 85 smaller dams on tributaries.<ref name="Pick-Sloan">{{cite web
|last=Reuss
|first=Martin
|url=http://140.194.76.129/publications/eng-pamphlets/ep870-1-42/c-4-2.pdf
|title=The Pick-Sloan Plan
|publisher=U.S. Army Corps of Engineers
|work=Engineer Pamphlets
|accessdate=2010-10-05}}</ref><ref name="Otstot">{{cite web
|author=Otstot, Roger S.
|url=http://mo-rast.org/wp-content/uploads/2011/09/2011.09.27-Continued-Pick-Sloan-Presentation-Roger-Otstot.pdf
|title=Pick-Sloan Missouri River Basin Program: Hydropower and Irrigation
|publisher=Missouri River Association of States and Tribes
|work=U.S. Bureau of Reclamation
|date=2011-09-27
|accessdate=2012-01-14}}</ref>

In the early stages of Pick–Sloan development, tentative plans were made to build a low dam on the Missouri at Riverdale, North Dakota and 27 smaller dams on the Yellowstone River and its tributaries.<ref>{{cite article
|title=Missouri River Basin: Report of a Committee of Two Representatives Each from the Corps of Engineers, U.S. Army, and the Bureau of Reclamation, Appointed to Review the Features Presented by the Corps of Engineers (House Document No. 475) and the Bureau of Reclamation (Senate Document No. 191) for the Comprehensive Development of the Missouri River Basin
|publisher=U.S. Congress
|work=78th Congress, 2nd Session
|date=1944-11-21}}</ref> This was met with controversy from inhabitants of the Yellowstone basin, and eventually the USBR proposed a solution: to greatly increase the size of the proposed dam at Riverdale – today's Garrison Dam, thus replacing the storage that would have been provided by the Yellowstone dams. Because of this decision, the Yellowstone is now the longest free-flowing river in the contiguous United States.<ref>{{cite web
|author=Bon, Kevin W.
|url=http://library.fws.gov/Wetlands/upperyellowstone_01.pdf
|title=Upper Yellowstone River Mapping Project
|publisher=U.S. Fish and Wildlife Service
|date=2001-07
|accessdate=2012-01-14}}</ref> In the 1950s, construction commenced on the five mainstem dams – Garrison, Oahe, [[Big Bend Dam|Big Bend]], [[Fort Randall Dam|Fort Randall]] and [[Gavins Point Dam|Gavins Point]] – proposed under the Pick-Sloan Plan.<ref name="Pick-Sloan"/> Along with Fort Peck, which was integrated as a unit of the Pick-Sloan Plan in the 1940s, these dams now form what is known as the Missouri River Mainstem System.<ref name="Mainstem">{{cite web
|author=Knofczynski, Joel 
|url=http://dnr.ne.gov/MissouriRiverActivities/pdf_files/MissouriRiver_MainstemSystem-Nov2010.pdf
|title=Missouri River Mainstem System 2010–2011 Draft Annual Operating Plan
|publisher=Nebraska Department of Natural Resources
|work=U.S. Army Corps of Engineers
|date=2010-11
|accessdate=2011-01-12}}</ref>

The six dams of the Mainstem System, chiefly Fort Peck, Garrison and Oahe, are among [[List of largest dams in the world|the largest dams in the world by volume]]; their sprawling reservoirs also rank within [[List of largest reservoirs in the United States|the biggest of the nation]].<ref>{{cite web
|url=http://www.ussdams.org/uscold_s.html
|title=Dam, Hydropower and Reservoir Statistics
|publisher=United States Society on Dams
|accessdate=2010-10-05}}</ref> Holding up to 74.1 million acre-feet (91.4&nbsp;km<sup>3</sup>) in total, the six reservoirs can store more than three year's worth of the river's flow as measured below Gavins Point, the lowermost dam.<ref name="MainstemSystem"/> This enormous capacity makes it the largest reservoir system in the United States and one of the largest in North America.<ref>{{cite web
|url=http://www.epa.gov/region07/citizens/care/missouri.htm
|title=The Missouri River Mainstem
|publisher=U.S. Environmental Protection Agency
|date=2011-04-15
|accessdate=2012-01-15}}</ref> In addition to storing irrigation water, the system also includes an annual flood-control reservation of 16.3 million acre-feet (20.1&nbsp;km<sup>3</sup>).<ref name="Mainstem"/> Mainstem power plants generate about 9.3 billion [[kilowatt hour|KWh]] annually – equal to a constant output of almost 1,100 [[megawatt]]s.<ref>{{cite news
|author=MacPherson, James
|url=http://news.yahoo.com/power-generation-missouri-river-dams-rebounds-182956078.html
|title=Power generation at Missouri River dams rebounds
|publisher=Yahoo! News
|agency=Associated Press
|date=2012-01-05
|accessdate=2012-01-14}}</ref> Along with nearly 100 smaller dams on tributaries, namely the [[Bighorn River|Bighorn]], Platte, Kansas, and Osage Rivers, the system provides irrigation water to nearly {{convert|7500|mi2|km2|abbr=on}} of land.<ref name="Pick-Sloan" /><ref>{{cite article
|last=Johnston
|first=Paul
|title=History of the Pick-Sloan Program
|publisher=American Society of Civil Engineers
|work=World Environmental and Water Resource Congress 2006
|url=http://cedb.asce.org/cgi/WWWdisplay.cgi?152895
|accessdate=2012-01-19}}</ref>

{| class="wikitable sortable collapsible collapsed"  style="width:47%; float:left;"
|-
!colspan=6|Dams on the Missouri River
|- style="font-size:9pt"
!Dam
!State(s)
!Height
!Reservoir
!Capacity<br>(Acre.ft)
!Capacity<br>([[Megawatt|MW]])
|- style="font-size:9pt"
!scope="row" |[[Toston Dam|Toston]]<ref>{{cite web|url=http://dnrc.mt.gov/wrd/water_proj/factsheets/toston_factsheet.pdf|title=Toston Dam (Broadwater-Missouri)|publisher=Montana Department of Natural Resources and Conservation|work=Water Projects Bureau|accessdate=2011-03-16}}</ref>
|MT
|{{nts|56}} ft<br>(17 m)
|
|3,000
| style="background:#eee8aa;"|10
|- style="font-size:9pt"
!scope="row" |[[Canyon Ferry Dam|Canyon Ferry]]<ref name="CanyonFerryDam"/>
|MT
|{{nts|225}} ft<br>(69 m)
|[[Canyon Ferry Lake]]
|1,973,000
|50
|- style="font-size:9pt"
!scope="row" |[[Hauser Dam|Hauser]]<ref name="Hauser"/>
|MT
|{{nts|80}} ft<br>(24 m)
|[[Hauser Lake]]
|98,000
|19
|- style="font-size:9pt"
!scope="row" |[[Holter Dam|Holter]]<ref name="HolterDam"/>
|MT
|{{nts|124}} ft<br>(38 m)
|[[Holter Lake]]
|243,000
|48
|- style="font-size:9pt"
!scope="row" |[[Black Eagle Dam|Black Eagle]]<ref name="BlackEagleDam"/>
|MT
|{{nts|13}} ft<br>(4.0 m)
|Long Pool{{#tag:ref|"Long Pool" is the name used by area residents to refer to the smooth, almost lake-like {{convert|55|mi|km|abbr=on}} stretch of the Missouri between the Black Eagle Dam and the town of [[Cascade, Montana|Cascade]]. Only about {{convert|2|mi|km|abbr=on}} of the so-called Long Pool are actually part of the impoundment behind the dam.|group=n}}
|2,000
| style="background:#eee8aa;"|21
|- style="font-size:9pt"
!scope="row" |[[Rainbow Dam|Rainbow]]<ref>{{cite web|url=http://www.pplmontana.com/producing+power/power+plants/Rainbow+Dam.htm|title=Rainbow Dam|publisher=PPL Montana|work=Producing Power|accessdate=2011-03-16}}</ref>
|MT
|{{nts|29}} ft<br>(8.8 m)
|
|1,000
| style="background:#eee8aa;"|36
|- style="font-size:9pt"
!scope="row" |[[Cochrane Dam|Cochrane]]<ref>{{cite web|url=http://www.pplmontana.com/producing+power/power+plants/Cochrane+Dam.htm|title=Cochrane Dam|publisher=PPL Montana|work=Producing Power|accessdate=2011-03-16}}</ref>
|MT
|{{nts|59}} ft<br>(18 m)
|
|3,000
| style="background:#eee8aa;"|64
|- style="font-size:9pt"
!scope="row" |[[Ryan Dam|Ryan]]<ref name="RyanDam"/>
|MT
|{{nts|61}} ft<br>(19 m)
|
|5,000
| style="background:#eee8aa;"|60
|- style="font-size:9pt"
!scope="row" |[[Morony Dam|Morony]]<ref>{{cite web|url=http://www.pplmontana.com/producing+power/power+plants/Morony+Dam.htm|title=Morony Dam|publisher=PPL Montana|work=Producing Power|accessdate=2011-03-16}}</ref>
|MT
|{{nts|59}} ft<br>(18 m)
|
|3,000
| style="background:#eee8aa;"|48
|- style="font-size:9pt"
! scope="row" style="background:#7fffd4;"|[[Fort Peck Dam|Fort Peck]]<ref>{{cite web|url=http://www.nwo.usace.army.mil/lake_proj/fortpeck/index.html|title=Fort Peck Dam/Fort Peck Lake|publisher=U.S. Army Corps of Engineers|work=Omaha District|accessdate=2011-03-16}}</ref>
|MT
|{{nts|250}} ft<br>(76 m)
|[[Fort Peck Lake]]
|18,690,000
|185
|- style="font-size:9pt"
! scope="row" style="background:#7fffd4;"|[[Garrison Dam|Garrison]]<ref>{{cite web|last=Wilson|first=Ron|url=http://gf.nd.gov/multimedia/ndoutdoors/issues/2003/jun/docs/garrison-dam.pdf|title=Garrison Dam: A Half-Century Later|publisher=North Dakota Game and Fish Department|work=ND Outdoors|date=2003-06|accessdate=2011-03-16|page=14}}</ref>
|ND
|{{nts|210}} ft<br>(64 m)
|[[Lake Sakakawea]]
|23,800,000
|515
|- style="font-size:9pt"
! scope="row" style="background:#7fffd4;"|[[Oahe Dam|Oahe]]<ref>{{cite web|url=http://www.nwo.usace.army.mil/lake_proj/MasterPlan/OaheMP.pdf|title=Final Oahe Dam/Lake Oahe Master Plan: Missouri River, South Dakota and North Dakota|publisher=U.S. Army Corps of Engineers|date=2010-09|accessdate=2012-01-17}}</ref>
|SD
|{{nts|245}} ft<br>(75 m)
|[[Lake Oahe]]
|23,500,000
|786
|- style="font-size:9pt"
! scope="row" style="background:#7fffd4;"|[[Big Bend Dam|Big Bend]]<ref>{{cite web|url=http://www.nwo.usace.army.mil/lake_proj/bigbend/powerdam.html|title=Big Bend Dam/Lake Sharpe|publisher=U.S. Army Corps of Engineers|work=Omaha District|accessdate=2012-03-12}}</ref>
|SD
|{{nts|95}} ft<br>(29 m)
|[[Lake Sharpe]]
|1,910,000
|493
|- style="font-size:9pt"
! scope="row" style="background:#7fffd4;"|[[Fort Randall Dam|Fort Randall]]<ref>{{cite web|url=http://www.nwo.usace.army.mil/lake_proj/fortrandall/powerdam.html|title=Fort Randall Dam/Lake Francis Case|publisher=U.S. Army Corps of Engineers|work=Omaha District|accessdate=2012-03-13}}</ref>
|SD
|{{nts|165}} ft<br>(50 m)
|[[Lake Francis Case]]
|5,700,000
|320
|- style="font-size:9pt"
! scope="row" style="background:#7fffd4;"|[[Gavins Point Dam|Gavins Point]]<ref>{{cite web|url=http://www.nwo.usace.army.mil/lake_proj/gavinspoint/powerdam.html|title=Gavins Point Dam/Lewis & Clark Lake|publisher=U.S. Army Corps of Engineers|work=Omaha District|accessdate=2012-03-12}}</ref>
|NE<br>SD
|{{nts|74}} ft<br>(23 m)
|[[Lewis and Clark Lake]]
|492,000
|132
|- style="font-size:9pt" class="sortbottom"
!scope="row" |'''Total'''
| style="background:beige;"|
| style="background:beige;"|
| style="background:beige;"|
| style="background:beige;"|76,436,000
| style="background:beige;"|2,787
|}

The table at left lists statistics of all fifteen dams on the Missouri River, ordered downstream.<ref name="ACMEmapper"/> Many of the run-of-the-river dams on the Missouri (marked in yellow) form very small impoundments which may or may not have been given names; those unnamed are left blank. <!-- Pick-Sloan dams are marked in green. --> All dams are on the upper half of the river above Sioux City; the lower river is uninterrupted due to its longstanding use as a shipping channel.<ref>{{cite web
|url=http://nd.water.usgs.gov/lewisandclark/dams.html
|title=Dams and Reservoirs on the Upper Missouri River
|publisher=U.S. Geological Survey
|work=North Dakota Water Science Center
|date=2009-12-10
|accessdate=2011-03-19}}</ref>

==Navigation==
<blockquote class="toccolours" style="text-align:justify; width:27%; float:right; padding:10px 15px; display:table;">"[Missouri River shipping] never achieved its expectations. Even under the very best of circumstances, it was never a huge industry."<br><small>~Richard Opper, former Missouri River Basin Association executive director<ref name="decline">{{cite news|url=|title=Long dry spells cut into Missouri River navigation|work=News Tribune|date=2010-05-26}}</ref></small></blockquote>
[[Image:Yellowstone (steamboat) aground.jpg|thumb|right|alt=Painting of a steamboat stranded on a sandbar in the middle of a swift-flowing river|Painting of the steamboat ''Yellowstone'', one of the earliest commercial vessels to run on the river, circa 1833. The dangerous currents in the river caused the ship to run aground on a [[sandbar]] in this illustration.]]
Boat travel on the Missouri started with the wood-framed canoes and [[bull boat]]s of the Native Americans, which were used for thousands of years before the introduction of larger craft to the river upon colonization of the Great Plains.<ref name="boats">{{cite web
|url=http://history.nd.gov/activities/riverboats.pdf
|title=Missouri River Boats
|publisher=State Historical Society of North Dakota
|accessdate=2012-01-28}}</ref> The first steamboat on the Missouri was the ''[[Independence (steamboat)|Independence]]'', which started running between St. Louis and [[Keytesville, Missouri]] around 1819.<ref name="D101">Demoth, p. 101</ref> By the 1830s, large mail and freight-carrying vessels were running regularly between Kansas City and St. Louis, and many traveled even farther upstream. A handful, such as the ''Western Engineer'' and the ''[[Yellowstone (steamboat)|Yellowstone]]'', were able to make it up the river as far as eastern Montana.<ref name="boats"/><ref>{{cite web
|author=Carlson, Gayle F.; Bozell, John R.; Pepperi, Robert
|url=http://www.nebraskahistory.org/archeo/pubs/Engineer%20Cantonment.pdf
|title=The Search For Engineer Cantonment
|publisher=Nebraska State Historical Society
|work=Explore Nebraska Archaeology  
|year=2004
|accessdate=2012-01-28}}</ref>

During the early 19th century, at the height of the fur trade, steamboats and [[keelboat]]s began traveling nearly the whole length of the Missouri from Montana's rugged Missouri Breaks to the mouth, carrying beaver and buffalo furs to and from the areas that the trappers frequented.<ref name="Boonslick"/> This resulted in the development of the [[Mackinaw boat#Development|Missouri River mackinaw]], which specialized in carrying furs. Since these boats could only travel downriver, they were dismantled and sold for lumber upon their arrival at St. Louis.<ref name="boats"/>

Water transport increased through the 1850s with multiple craft ferrying pioneers, emigrants and miners; many of these runs were from St. Louis or Independence to near Omaha. There, most of these people would set out overland along the large but shallow and unnavigable Platte River, which was described by pioneers as "a mile wide and an inch deep" and "the most magnificent and useless of rivers".<ref>Rogers, Brown and Garbrecht, p. 113</ref> Steamboat navigation peaked in 1858 with over 130 boats operating full-time on the Missouri, with many more smaller vessels.<ref name="Dyer2">Dyer, p. 2</ref> Many of the earlier vessels were built on the Ohio River before being transferred to the Missouri. Side-wheeler steamboats were preferred over the larger sternwheelers used on the Mississippi and Ohio because of their greater maneuverability.<ref name="Boonslick">{{cite journal
|author= Dyer, Robert L.
|title=A Brief History of Steamboating on the Missouri River with Emphasis on the Boonslick Region
|journal=Boone's Lick Heritage
|volume=5
|date=1997-06
|url=http://www.riverboatdaves.com/docs/moboats.html
|issue=2}}</ref>

[[File:Missouri river at hwy 364.jpg|thumb|A barge travels North on the Missouri River at Highway 364 in Saint Charles, Missouri.]]

The industry's success, however, did not guarantee safety. In the early decades before the river's flow was controlled by man, its sketchy rises and falls and its massive amounts of sediment, which prevented a clear view of the bottom, wrecked some 300 vessels. Because of the dangers of navigating the Missouri River, the average ship's lifespan was short, only about four years.<ref name="Dyer2"/> The development of the Transcontinental and [[Northern Pacific Railroad|Northern Pacific]] Railroads marked the beginning of the end of steamboat commerce on the Missouri. Outcompeted by trains, the number of boats slowly dwindled, until there was almost nothing left by the 1890s. Transport of agricultural and mining products by barge, however, saw a revival in the early twentieth century.<ref>{{cite news
|last=Handwerk
|first=Brian
|title=Steamboat Wreck Sheds Light on Bygone Era
|work=National Geographic News
|page=2
|date=2002-11-18}}</ref><ref>{{cite web
|url=http://www.nebraskastudies.org/0400/frameset_reset.html?http://www.nebraskastudies.org/0400/stories/0401_0141.html
|title=Routes West: The Mighty Mo
|publisher=nebraskastudies.org
|page=2
|accessdate=2010-10-17}}</ref>

===Passage to Sioux City===
Since the beginning of the 20th century, the Missouri River has been extensively engineered for water transport purposes, and about 32&nbsp;percent of the river now flows through artificially straightened channels.<ref name="Story"/> In 1912, the USACE was authorized to maintain the Missouri to a depth of six feet (1.8 m) from the Port of Kansas City to the mouth, a distance of {{convert|368|mi|km}}.<ref name="ACMEmapper"/> This was accomplished by constructing levees and [[wing dam]]s to direct the river’s flow into a straight, narrow channel and prevent sedimentation. In 1925, the USACE began a project to widen the river's navigation channel to {{convert|200|ft|m}}; two years later, they began dredging a deep-water channel from Kansas City to Sioux City. These modifications have reduced the river's length from some {{convert|2540|mi|km}} in the late 19th century to {{convert|2341|mi|km}} in the present day.<ref name="modifications"/><ref>{{cite web
|url=http://www.rivers.gov/waterfacts.html
|title=Rivers and Water Trivia
|publisher=National Wild And Scenic Rivers
|accessdate=2010-10-01}}</ref>

[[File:Gavins Point Dam.jpg|thumb|right|alt=Side view of a dam surrounded by green hills under a clear sky|[[Gavins Point Dam]] at [[Yankton, South Dakota]] is the uppermost obstacle to navigation from the mouth on the Missouri today.]]
Construction of dams on the Missouri under the Pick-Sloan Plan in the mid-twentieth century was the final step in aiding navigation. The large reservoirs of the Mainstem System help provide a dependable flow to maintain the navigation channel year-round, and are capable of halting most of the river's annual freshets.<ref>{{cite web
|url=http://www.nwk.usace.army.mil/projects/mitigation/projectistory.htm
 |title=Missouri River Bank Stabilization and Navigation Project
|publisher=U.S. Army Corps of Engineers
|work=Missouri River Mitigation Project
|date=2004-07-21
|accessdate=2010-10-07 |archiveurl = http://web.archive.org/web/20070211195723/http://www.nwk.usace.army.mil/projects/mitigation/projectistory.htm |archivedate = 2007-02-11}}</ref> However, high and low water cycles of the Missouri – notably the protracted early-21st-century drought in the Missouri River basin<ref>{{cite news
|author=O'Driscoll, Patrick; Kenworthy, Tom
|url=http://www.usatoday.com/news/nation/2005-04-28-muddy_x.htm
|title=Western drought shrinking Big Muddy
|work=USA Today
|date=2005-04-28
|accessdate=2012-01-14}}</ref> and historic floods in 1993<ref>{{cite web
|author=Larson, Lee W.
|url=http://www.nwrfc.noaa.gov/floods/papers/oh_2/great.htm
|title=The Great USA Flood of 1993
|publisher=National Oceanic and Atmospheric Administration
|work=Destructive Water: Water-Caused Natural Disasters – Their Abatement and Control 
|accessdate=2012-01-14}}</ref> and 2011<ref name="2011flood1">{{cite news
|url=http://www.msnbc.msn.com/id/43271554/ns/weather/t/blame-game-rising-river-nears-sd-homes/
|title=Blame game as rising river nears SD homes: Some residents say corps erred in not releasing water sooner
|publisher=MSNBC
|date=2011-06-03
|accessdate=2012-01-14}}</ref> – are difficult for even the massive Mainstem System reservoirs to control.<ref name="2011flood1"/>

In 1945, the USACE began the Missouri River Bank Stabilization and Navigation Project, which would permanently increase the river’s navigation channel to a width of {{convert|300|ft|m}} and a depth of nine feet (2.7 m). During work that continues to this day, the {{convert|735|mi|km|adj=on}} navigation channel from Sioux City to St. Louis has been controlled by building rock dikes to direct the river’s flow and scour out sediments, sealing and cutting off meanders and side channels, and dredging the riverbed.<ref>{{cite web
|url=http://www.nwk.usace.army.mil/projects/mitigation/bankstabilization.htm
 |title=Missouri River Mitigation Project
|publisher= U.S. Army Corps of Engineers
|date=2004-07-21
|accessdate=2010-10-07 |archiveurl = http://web.archive.org/web/20070627040444/http://www.nwk.usace.army.mil/projects/mitigation/bankstabilization.htm |archivedate = 2007-06-27}}</ref> However, the Missouri has often resisted the efforts of the USACE to control its depth. In 2006, several [[U.S. Coast Guard]] boats ran aground in the Missouri River because the navigation channel had been severely silted.<ref>{{cite web
|url=http://ago.mo.gov/newsreleases/2006/072606.htm
|title=Corps failing to keep Missouri River navigation open as promised, Nixon says; AG demands to know plan
|publisher=Missouri Attorney General
|date=2006-07-26
|accessdate=2010-10-07}}</ref> The USACE was blamed for failing to maintain the channel to the minimum depth.<ref>{{cite web
|url=http://ago.mo.gov/pdf/2006/MartinLetter072606.pdf
|title=Letter from Missouri Attorney General Jeremiah W. Nixon to Brigadier General Gregg. F Martin
|publisher=Missouri Attorney General
|date=2006-07-26
|accessdate=2010-10-07}}</ref>

[[File:Missouririver1.jpg|thumb|left|200px|alt=Aerial view of a brownish river winding through an agricultural valley|The Missouri River near [[New Haven, Missouri]], looking upstream – note the [[riprap]] wing dam protruding into the river from the left to direct its flow into a narrower channel]]
[[File:Missouri-Floyd Rivers Sioux City Iowa.jpg|thumb|left|200px|alt=View of two rivers meeting in the middle of an industrial area|The Missouri River at Sioux City, IA, near the upper most navigable reach of the river today]]
In 1929, the [[Missouri River Navigation Commission]] estimated the total amount of goods shipped on the river annually at 15 million tons (13.6 million metric tons), providing widespread consensus for the creation of a navigation channel. However, shipping traffic has since been far lower than expected – shipments of commodities including produce, manufactured items, lumber, and oil averaged only 683,000 tons (616,000 t) per year from 1994 to 2006.<ref name="GAO">{{cite web
|url=http://www.gao.gov/new.items/d09224r.pdf
|title=Missouri River Navigation: Data on Commodity Shipments for Four States Served by the Missouri River and Two States Served by Both the Missouri and Mississippi Rivers
|publisher=U.S. Government Accountability Office
|date=2009-01-15
|accessdate=2010-10-07}}</ref> 

By tonnage of transported material, Missouri is by far the largest user of the river accounting for 83&nbsp;percent of river traffic, while Kansas has 12&nbsp;percent, Nebraska three&nbsp;percent and Iowa two&nbsp;percent. Almost all of the barge traffic on the Missouri River ships sand and gravel dredged from the lower {{convert|500|mi|km}} of the river; the remaining portion of the shipping channel now sees little to no use by commercial vessels.<ref name="GAO"/>

===Traffic decline===
Tonnage of goods shipped by barges on the Missouri River has seen a serious decline from the 1960s to the present. In the 1960s, the USACE predicted an increase to 12 million short tons (10.8 million t) per year by 2000, but instead the opposite has happened. The amount of goods plunged from 3.3 million short tons (3 million t) in 1977 to just 1.3 million short tons (1.18 million t) in 2000.<ref>{{cite web
|last=Baumel
|first=C. Phillip
|last1=Van Der Kamp
|first1=Jerry
|url=http://www.iatp.org/files/Past_and_Future_Grain_Traffic_on_the_Missouri_.pdf
|title=Past and Future Grain Traffic on the Missouri River
|publisher=Institute for Agriculture and Trade Policy
|date=2003-07
|accessdate=2010-10-07}}</ref> One of the largest drops has been in agricultural products, especially wheat. Part of the reason is that irrigated land along the Missouri has only been developed to a fraction of its potential.<ref name="Prairiefire"/> In 2006, barges on the Missouri hauled only 200,000 short tons (180,000 t) of products which is equal to the amount of ''daily'' freight traffic on the Mississippi.<ref name="Prairiefire">{{cite news
|url=http://www.prairiefirenewspaper.com/2007/12/missouri-river
|title=The Missouri River: A view from upstream
|work=Prairie Fire
|date=2007-12
|accessdate=2010-10-07}}</ref>

Drought conditions in the early 21st century and competition from other modes of transport – mainly railroads – are the primary reason for decreasing river traffic on the Missouri. The failure of the USACE to consistently maintain the navigation channel has also hampered the industry. Currently, efforts are being made to revive the shipping industry on the Missouri River, because of the efficiency and cheapness of river transport to haul agricultural products, and the overcrowding of alternative transportation routes. Solutions such as expanding the navigation channel and releasing more water from reservoirs during the peak of the navigation season are being considered.<ref>{{cite web
|last=Jorgensen
|first=Nancy
|url=http://www.mfa-inc.com/web/guest/LetRiverRoll
|title=Let the river roll: MODOT studies ways to increase waterway freight
|publisher=MFA Incorporated
|archiveurl=http://web.archive.org/web/20110725063506/http://www.mfa-inc.com/web/guest/LetRiverRoll
|archivedate=2011-07-25
|accessdate=2010-10-07}}</ref><ref>{{cite web
|url=http://www.edf.org/documents/2233_MissouriDamNavigation.pdf
|title=Missouri River Dam Reforms and Navigation
|publisher=Environmental Defense Fund 
|archivedate=2008-12-01
|archiveurl=http://web.archive.org/web/20081201080801/http://www.edf.org/documents/2233_MissouriDamNavigation.pdf
|accessdate=2011-01-18}}</ref> Drought conditions lifted in 2010, in which about 334,000 short tons (301,000 t) were barged on the Missouri, representing the first significant increase in shipments since 2000. However, flooding in 2011 closed record stretches of the river to boat traffic – "wash[ing] away hopes for a bounce-back year."<ref>{{cite news
|author=Schick, Anthony
|title=Missouri River flooding hurts barge industry: After years of drought, flooding ruins expectations for recovery of shipping
|url=http://www.columbiamissourian.com/stories/2011/07/23/missouri-river-flooding-closure-impacting-barge-industry/
|work=Missourian
|date=2011-07-23
|accessdate=2012-01-21}}</ref>

==Ecology==

===Natural history===
[[File:Missouririverecoregions.jpg|thumb|right|240px|alt=Map showing the three freshwater ecoregions of the Missouri River basin|Freshwater [[ecoregion]]s of the Missouri basin]]
Historically, the thousands of square miles that comprised the floodplain of the Missouri River supported a wide range of plant and animal species. Biodiversity generally increased proceeding downstream from the cold, subalpine headwaters in Montana to the temperate, moist climate of Missouri. Today, the river's [[riparian zone]] consists primarily of [[Hibiscus tiliaceus|cottonwood]]s, [[willow]]s and [[Platanus|sycamore]]s, with several other types of trees such as [[maple]] and [[Fraxinus|ash]].<ref name="RNA436">Benke and Cushing, p. 436</ref> Average tree height generally increases farther from the riverbanks for a limited distance, as land adjacent to the river is vulnerable to soil erosion during floods. Because of its large sediment concentrations, the Missouri does not support many aquatic invertebrates.<ref name="RNA436" /> However, the basin does support about 300 species of birds<ref name="RNA436"/> and 150 species of fish,<ref>{{cite web
|url=http://www.npwrc.usgs.gov/resource/fish/othrfish/overview.htm
|title=The Missouri River System's "Other" Fish
|publisher=Northern Prairie Wildlife Research Center
|date=2006-08-03
|accessdate=2010-10-08}}</ref> some of which are [[endangered species|endangered]] such as the [[Pallid sturgeon]]. The Missouri's aquatic and riparian habitats also support several species of mammals, such as [[mink]]s, river otters, beavers, [[muskrat]]s, and [[raccoon]]s.<ref name="RNA438">Benke and Cushing, p. 438</ref> 

The [[World Wide Fund For Nature]] divides the Missouri River watershed into three freshwater [[ecoregion]]s: the Upper Missouri, Lower Missouri and Central Prairie. The Upper Missouri, roughly encompassing the area within Montana, Wyoming, southern Alberta and Saskatchewan, and North Dakota, comprises mainly semiarid [[shrub-steppe]] grasslands with sparse biodiversity because of [[Ice Age]] [[glaciation]]s. There are no known [[endemic species]] within the region. Except for the headwaters in the Rockies, there is little precipitation in this part of the watershed.<ref>{{cite web
|url=http://www.feow.org/ecoregion_details.php?eco=142
|title=Upper Missouri
|publisher=Freshwater Ecoregions of the World
|date=2010-08-26
|accessdate=2010-10-08}}</ref> The Middle Missouri ecoregion, extending through Colorado, southwestern Minnesota, northern Kansas, Nebraska, and parts of Wyoming and Iowa, has greater rainfall and is characterized by temperate forests and grasslands. Plant life is more diverse in the Middle Missouri, which is also home to about twice as many animal species.<ref>{{cite web
|url=http://www.feow.org/ecoregion_details.php?eco=142
|title=Middle Missouri
|publisher=Freshwater Ecoregions of the World
|date=2010-08-26
|accessdate=2010-10-08}}</ref> Finally, the Central Prairie ecoregion is situated on the lower part of the Missouri, encompassing all or parts of Missouri, Kansas, Oklahoma and Arkansas. Despite large seasonal temperature fluctuations, this region has the greatest diversity of plants and animals of the three. Thirteen species of [[crayfish]] are endemic to the lower Missouri.<ref>{{cite web
|url=http://www.feow.org/ecoregion_details.php?eco=146
|title=Central Prairie
|publisher=Freshwater Ecoregions of the World
|date=2010-08-26
|accessdate=2010-10-08}}</ref>

===Human impacts===
[[File:Mo River Courthouse, GF Montana 2.jpg|thumb|Missouri River as it flows through [[Great Falls, Montana]]]]
Since the beginning of river commerce and industrial development in the 1800s, the Missouri has been severely polluted and its water quality degraded by human activity. Most of the river's floodplain habitat is long gone, replaced by irrigated agricultural land. Development of the floodplain has led to increasing amounts of people and infrastructure within areas at high risk of inundation. Levees have been constructed along more than a third of the river in order to keep floodwater within the channel, but with the consequences of faster stream velocity and a resulting increase of peak flows in downstream areas. [[Fertilizer]] runoff, which causes elevated levels of nitrogen and other nutrients, is a major problem along the Missouri River, especially in Iowa and Missouri. This form of pollution also heavily affects the upper Mississippi, [[Illinois River|Illinois]] and Ohio Rivers. Low oxygen levels in rivers and the vast [[Gulf of Mexico dead zone]] at the end of the Mississippi Delta are both results of high nutrient concentrations in the Missouri and other tributaries of the Mississippi.<ref>{{cite web
|last=Booth
|first=Mary
|url=http://www.ewg.org/reports/deadzone
|title=Dead in the Water
|publisher=Environmental Working Group
|date=2006-04
|accessdate=2010-10-17}}</ref><ref>Singer, pp. 80–85</ref>

[[File:Nishnabotna River aerial.jpg|thumb|left|187px|alt=View of the confluence of two rivers in an agricultural area|Agricultural fields dominate most of the former [[floodplain]], including this area around the Missouri's confluence with the [[Nishnabotna River]] in western Missouri.]]
Channelization of the lower Missouri waters has made the river narrower, deeper and less accessible to riparian flora and fauna. Numerous dams and bank stabilization projects have been constructed to facilitate the conversion of {{convert|300000|acre|km2}} of Missouri River floodplain to agricultural land. Channel control has significantly reduced the volume of sediment transported downstream by the river and eliminated critical habitat for fish, birds and amphibians.<ref name="riparianloss">{{cite web|last=Kendle|first=Earl R.|url= http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1022&context=nebgamewhitepap|title=The Effects of Channelization in the Missouri River on Fish and Fish-Food Organisms|publisher=Digital Commons @ University of Nebraska, Lincoln|work=Nebraska Game and Parks Commission|date=1970-11-09|accessdate=2010-10-20}}</ref> By the early 21st century, declines in populations of native species prompted the [[U.S. Fish and Wildlife Service]] to issue a biological opinion recommending restoration of river habitats for federally endangered bird and fish species.<ref>{{cite web
|url=http://www.fws.gov/mountain-prairie/pressrel/03-87.htm
|title=Executive Summary
|publisher=U.S. Army Corps of Engineers
|work=U.S. Fish and Wildlife Service Biological Opinion on the Operation of the Missouri River Main Stem Reservoir System, Operation and Maintenance of the Missouri River Bank Stabilization and Navigation Project, and Operation of the Kansas River Reservoir System
|accessdate=2011-01-19}}</ref>

The USACE began work on ecosystem restoration projects along the lower Missouri River in the early 21st century. Because of the low use of the shipping channel in the lower Missouri maintained by the USACE, it is now considered feasible to remove some of the levees, dikes, and wing dams that constrict the river’s flow, thus allowing it to naturally restore its banks.<ref name="riparianloss"/> As of 2001, there were {{convert|87000|acre|km2}} of riverside floodplain undergoing active restoration.<ref>{{cite news
|title=Missouri River tops annual rating of threatened waterways
|publisher=U.S. Water News
|year=2001–05
|accessdate=2010-10-17
|url=http://www.uswaternews.com/archives/arcpolicy/1misriv5.html}}</ref>

Restoration projects have re-mobilized some of the sediments that had been trapped behind bank stabilization structures, prompting concerns of exacerbated nutrient and sediment pollution locally and downstream in the northern Gulf of Mexico. A 2010 [[United States National Research Council|National Research Council]] report assessed the roles of sediment in the Missouri River, evaluating current habitat restoration strategies and alternative ways to manage sediment.<ref>{{cite web
|url=http://dels.nas.edu/Report/Missouri-River-Planning-Recognizing-Incorporating/13019 
|title=Missouri River Planning Report
|publisher=National Research Council
|year=2010
|accessdate=2011-07-22}}</ref> The report found that a better understanding of sediment processes in the Missouri River, including the creation of a “sediment budget” – an accounting of sediment transport, erosion, and deposition volumes for the length of the Missouri River – would provide a foundation for projects to improve water quality standards and protect endangered species.<ref>{{cite web
|url=http://dels.nas.edu/Materials/Report-In-Brief/4336-Missouri-River-Planning 
|title=Missouri River Planning Report in Brief
|publisher= National Research Council 
|work=Division on Earth & Life Studies
|year=2010
|accessdate=2011-07-22}}</ref>

==Tourism and recreation==
[[File:MNRR At the North Alabama wreck site 20070807171612.jpg|thumb|right|alt=View of a river winding past a sandbar with people on the shore|Part of the [[Missouri National Recreational River]], a {{convert|98|mi|km|adj=on}} preserved stretch of the Missouri on the border of South Dakota and Nebraska]]
With over {{convert|1500|mi2|km2|abbr=on}} of open water, the six reservoirs of the Missouri River Mainstem System provide some of the main recreational areas within the basin. Visitation has increased from 10 million visitor-hours in the mid-1960s to over 60 million visitor-hours in 1990.<ref name="Prairiefire"/> Development of visitor facilities was spurred by the Federal Water Project Recreation Act of 1965, which required the USACE to build and maintain boat ramps, campgrounds and other public facilities along major reservoirs.<ref name="MainstemSystem"/> Recreational use of Missouri River reservoirs is estimated to contribute $85–100 million to the regional economy each year.<ref name="TodaysMissouri">{{cite web
|url=http://www.swc.state.nd.us/4dlink9/4dcgi/GetSubCategoryPDF/201/TodaysMissouriRiver.pdf
|title=Today's Missouri River: A North Dakota Perspective
|publisher=North Dakota State Water Commission
|year=2008
|accessdate=2012-01-16}}</ref>

The [[Lewis and Clark National Historic Trail]], some {{convert|3700|mi|km}} long, follows nearly the entire Missouri River from its mouth to its source, retracing the route of the Lewis and Clark Expedition. Extending from [[Wood River, Illinois]] in the east to [[Astoria, Oregon]] in the west, it also follows portions of the Mississippi and Columbia Rivers. The trail, which spans through eleven U.S. states, is maintained by various federal and state government agencies; it passes through some 100 historic sites, notably archaeological locations including the [[Knife River Indian Villages National Historic Site]].<ref>{{cite web|url=http://www.nps.gov/lecl/planyourvisit/index.htm|title=Lewis and Clark National Historic Trail|publisher=U.S. National Park Service|accessdate=2010-10-11}}</ref><ref>{{cite web|url=http://www.npca.org/stateoftheparks/lewis_clark_trail/LECL-chapter.pdf|title=Lewis and Clark National Historic Trail|page=1|publisher=National Parks Conservation Association |archiveurl=http://web.archive.org/web/20100820214257/http://www.npca.org/stateoftheparks/lewis_clark_trail/LECL-chapter.pdf|archivedate=2010-08-20|accessdate=2010-10-11}}</ref>

Parts of the river itself are designated for recreational or preservational use. The [[Missouri National Recreational River]] consists of portions of the Missouri downstream from Fort Randall and Gavins Point Dams that total {{convert|98|mi|km}}.<ref>{{cite web
|url=http://www.nps.gov/mnrr/planyourvisit/canoeing-and-kayaking.htm
|title=Canoeing and Kayaking
|publisher=U.S. National Park Service
|accessdate=2010-10-11}}</ref><ref>{{cite web
|url=http://www.nps.gov/mnrr/index.htm
|title=Missouri National Recreational River
|publisher=U.S. National Park Service
|accessdate=2010-10-11}}</ref> These reaches exhibit islands, meanders, sandbars, underwater rocks, [[Riffle-pool sequence|riffles]], [[Snag (ecology)|snags]], and other once-common features of the lower river that have now disappeared under reservoirs or have been destroyed by channeling. About forty-five steamboat wrecks are scattered along these reaches of the river.<ref>{{cite web
|url=http://www.nature.nps.gov/water/planning/Info_Issuesoverview_reports/MNRR_IssuesOverview.pdf
|title=Missouri National Recreational River Water Resources Information and Issues Overview Report
|publisher=U.S. National Park Service
|accessdate=2010-10-11}}</ref><ref>{{cite web
|url=http://snr.unl.edu/gpcesu/PDFs/Shipwrecks_missouri.pdf
|title=No Ordinary Sensations of Pride and Pleasure: Shipwrecks and Related Sites Between Fort Randall, South Dakota and Sioux City, Iowa – Missouri River
|publisher=University of Nebraska Lincoln
|accessdate=2012-01-16
|author=Corbin, Annalies; Valvano, Christopher F.; Piero, Jacqueline D.}}</ref>

Downstream from Great Falls, Montana, about {{convert|149|mi|km}} of the river course through a rugged series of canyons and badlands known as the Missouri Breaks. This part of the river, designated a U.S. [[National Wild and Scenic River]] in 1976, flows within the [[Upper Missouri Breaks National Monument]], a {{convert|375000|acre|km2|adj=on}} preserve comprising steep cliffs, deep gorges, arid plains, badlands, archaeological sites, and whitewater rapids on the Missouri itself. The preserve includes a wide variety of plant and animal life; recreational activities include boating, rafting, hiking and wildlife observation.<ref>{{cite web
|url=http://www.blm.gov/pgdata/content/mt/en/fo/umrbnm.html
|title=Upper Missouri River Breaks National Monument
|publisher=U.S. Bureau of Land Management
|work=National System of Public Lands
|date=2010-09-13
|accessdate=2010-10-12}}</ref><ref>{{cite web
|url=http://www.missouribreaks.org/PDFs/twsmap2.pdf
|title=Upper Missouri River Breaks National Monument
|publisher=Friends of the Missouri Breaks National Monument
|format=PDF
|accessdate=2010-10-12}}</ref>

In north-central Montana, some {{convert|1100000|acre|km2}} along over {{convert|125|mi|km}} of the Missouri River, centering around [[Fort Peck Lake]], comprise the [[Charles M. Russell National Wildlife Refuge]].<ref>{{cite web
|url=http://www.fws.gov/cmr/
|title=Charles M. Russell National Wildlife Refuge
|publisher=U.S. Fish and Wildlife Service
|accessdate=2010-10-11}}</ref> The wildlife refuge consists of a native northern Great Plains ecosystem that has not been heavily affected by human development, except for the construction of Fort Peck Dam. Although there are few designated trails, the whole preserve is open to hiking and camping.<ref>{{cite web
|url=http://www.fws.gov/refuges/profiles/index.cfm?id=61520
|title=Charles M. Russell National Wildlife Refuge Overview
|publisher=U.S. Fish and Wildlife Service
|accessdate=2010-10-11}}</ref>

Many U.S. national parks, such as [[Glacier National Park (U.S.)|Glacier National Park]], [[Rocky Mountain National Park]], [[Yellowstone National Park]] and [[Badlands National Park]] are in the watershed. Parts of other rivers in the basin are set aside for preservation and recreational use – notably the [[Niobrara National Scenic River]], which is a {{convert|76|mi|km|adj=on}} protected stretch of the Niobrara River, one of the Missouri's longest tributaries.<ref>{{cite web
|url= http://www.nps.gov/niob/naturescience/index.htm
|title=Nature & Science
|publisher=U.S. National Park Service
|work=Niobrara National Scenic River
|date=2009-05-28
|accessdate=2010-10-12}}</ref> The Missouri flows through or past many [[National Historic Landmark]]s, which include [[Missouri Headwaters State Park|Three Forks of the Missouri]],<ref>{{cite web
|url=http://www.nps.gov/nr/travel/lewisandclark/thr.htm
|title=Three Forks of the Missouri
|publisher=U.S. National Park Service
|work=Lewis and Clark Expedition
|accessdate=2011-02-24}}</ref> [[Fort Benton, Montana]],<ref>{{cite web
|url=http://www.blm.gov/mt/st/en/fo/umrbnm/ftbenton.html
|title=Fort Benton National Historic Landmark
|publisher=U.S. Bureau of Land Management
|work=Upper Missouri River Breaks National Monument
|date=2010-03-09
|accessdate=2011-03-03}}</ref> [[Big Hidatsa Village Site]],<ref>{{cite web|url=http://tps.cr.nps.gov/nhl/detail.cfm?ResourceId=436&ResourceType=Site|title=Big Hidatsa Village Site|publisher=U.S. National Park Service|work=National Historic Landmark Summary Listing|accessdate=2011-03-16}}</ref> [[Fort Atkinson (Nebraska)|Fort Atkinson, Nebraska]]<ref>{{cite web
|url=http://www.nps.gov/nr/travel/lewisandclark/atk.htm
|title=Fort Atkinson
|publisher=U.S. National Park Service
|work=Lewis and Clark Expedition
|accessdate=2011-03-03}}</ref> and [[Arrow Rock Historic District]].<ref>{{cite web
|url=http://mostateparks.com/park/arrow-rock-state-historic-site
|title=Arrow Rock State Historic Site
|publisher=Missouri State Parks
|accessdate=2011-03-03}}</ref>

{{Wide image|Cow_Creek_flows_into_Missouri,_near_Cow_Island_in_Missouri_Breaks,_Blaine_County,_Montana.JPG|870px|<center>The Missouri River in [[Upper Missouri Breaks National Monument]], Montana, at the confluence with [[Cow Creek (Montana)|Cow Creek]]</center>}}

==See also==
{{div col|colwidth=20em}}
*''[[Across the Wide Missouri]]''
*[[List of longest main-stem rivers in the United States]]
*[[List of crossings of the Missouri River]]
*[[List of populated places along the Missouri River]]
*[[Montana Stream Access Law]]
*[[Montana Wilderness Association]]
*[[Sacagawea]]
{{div col end}}
{{Portal bar|Geography|United States|Montana|North Dakota|South Dakota|Nebraska|Iowa|Kansas|Missouri}}
{{clear}}

==Notes==
{{reflist|group= n}}

==References==
{{reflist|2|colwidth=30em}}

==Works cited==
{{refbegin|30em}}
*{{cite book
|last=Athearn
|first=Robert G.
|title=High country empire: the high plains and Rockies
|publisher=University of Nebraska Press
|year=1965
|isbn=0-8032-5008-8}}
*{{cite book
|last=Baldridge
|first=W. Scott
|title=Geology of the American Southwest: a journey through two billion years of plate-tectonic history
|publisher=Cambridge University Press
|year=2004
|isbn=0-521-01666-5}}
*{{cite book
|last1=Benke
|first1=Arthur C.
|last2=Cushing
|first2=Colbert E.
|title=Rivers of North America
|publisher=Academic Press
|year=2005
|isbn=0-12-088253-1}}
*{{cite book
|last=Cech
|first=Thomas V.
|title=Principles of Water Resources: History, Development, Management, and Policy
|publisher=John Wiley and Sons
|year=2009
|isbn=0-470-13631-6}}
*{{cite book
|last=Christensen
|first=Lawrence O.
|title=Dictionary of Missouri biography
|publisher=University of Missouri Press
|year=1999
|isbn=0-8262-1222-0}}
*{{cite book
|last=Demoth
|first=I. MacDonald
|title=The History of Pettis County, Missouri
|year=1882}}
*{{cite book
|last=Dick
|first=Everett
|title=Tales of the Frontier: From Lewis and Clark to the Last Roundup
|publisher=University of Nebraska Press
|year=1971
|isbn=0-8032-5744-9}}
*{{cite book
|last=Edwards
|first=Elwyn Hartley
|title=Horses: their role in the history of man
|publisher=Willow Books
|year=1987|isbn=0-00-218216-5}}
*{{cite book
|author=Federal Writers' Project
|title=Montana: A State Guide Book
|publisher=U.S. History Publishers
|isbn=1-60354-025-3}}
*{{cite book
|title=Wild mammals of North America: biology, management, and conservation
|publisher=JHU Press
|year=2003
|isbn=0-8018-7416-5
|author=Feldhamer, George A.; Thompson, Bruce Carlyle; Chapman, Joseph A.}}
*{{cite book
|last=Greene
|first=Jerome A.
|title=Battles and Skirmishes of the Great Sioux War, 1876–1877: The Military View
|publisher=University of Oklahoma Press
|year=2003
|isbn=0-8061-2669-8}}
*{{cite book
|last=Houck
|first=Louis
|title=A history of Missouri from the earliest explorations and settlements until the admission of the state into the union
|volume=1
|publisher=R.R. Donnelley and Sons, Co.
|year=1908|isbn=0-405-02856-3}}
*{{cite book
|last=Kellogg
|first=Louis Phelps
|title=Early narratives of the Northwest, 1634–1699
|publisher=C. Scribners's Sons
|volume=18
|year=1917
|isbn=}}
*{{cite book
|last=King
|first=Philip B.
|title=The Evolution of North America
|publisher=Princeton University Press
|edition=Revised
|year=1971
|isbn=}}
*{{cite book
|last=Lott
|first=Dale F.
|last1=Greene
|first1=Harry W.
|title=American Bison: A Natural History
|publisher=University of California Press
|year=2003
|isbn=0-520-24062-6}}
*{{cite book
|last=Mattes
|first=Merrill J.
|title=The Great Platte River Road: The Covered Wagon Mainline Via Fort Kearny to Fort Laramie
|publisher=University of Nebraska Press
|year=1987
|isbn=0-8032-8153-6}}
*{{cite book
|last=McFarlan
|first=Donald
|last1=McWhirter
|first1=Norris
|title=Guinness Book of World Records
|publisher=Bantam Books
|year=1992
|isbn=0-553-29537-3}}
*{{cite book
|editor=Morris, Charles
|title=Twentieth Century Encyclopædia: A Library of Universal Knowledge
|volume=5
|publisher=Syndicate Publishing Co.
|year=1912}}
*{{cite book
|last=Mulvaney
|first=Tom
|title=Helena
|publisher=Arcadia Publishing
|year=2008
|isbn=0-7385-5977-6}}
*{{cite book
|last=Roberts
|first=David C.
|last1=Hodsdon
|first1=W. Grant
|title= A Field Guide to Geology: Eastern North America
|publisher=Houghton Mifflin Harcourt
|year=2001
|isbn=0-618-16438-3}}
*{{cite book
|title=Water Resources and Environmental History
|publisher=ASCE Publications
|year=2004
|isbn=0-7844-0738-X|author = Rogers, Jerry R.; Brown, Glenn Owen; Garbrecht, Jürgen}}
*{{cite book
|last=Singer
|first=Siegfried Fred
|title=Global effects of environmental pollution: a symposium organized by the American Association for the Advancement of Science
|publisher=Springer
|year=1970
|isbn=90-277-0151-2}}
*{{cite book
|author=South Dakota State Historical Society, South Dakota Department of History
|title=South Dakota historical collections
|volume=1
|publisher=State Publishing Co
|year=1902}}
*{{cite book
|last=Sunder
|first=John E.
|title=The Fur Trade on the Upper Missouri, 1840–1865
|publisher=University of Oklahoma Press
|year=1993
|isbn=0-8061-2566-7}}
*{{cite book
|last=Thornbury
|first=W.
|title=Regional geomorphology of the United States
|publisher=John Wiley and Sons
|year=1965|isbn=0-471-86200-2}}
{{refend}}

==Further reading==
*{{cite book|author=Committee on Missouri River Ecosystem Science, National Research Council|title=The Missouri River ecosystem: exploring the prospects for recovery|publisher=National Academies Press|year=2002|isbn=0-309-08314-1}}
*{{cite book|author=Committee on Missouri River Recovery and Associated Sediment Management Issues, National Research Council|title=Missouri River Planning: Recognizing and Incorporating Sediment Management|publisher=National Academies Press|year=2010}}
*{{cite book|title=Exploring the Great Rivers of North America|publisher=National Geographic Society|year=1999|isbn=0-7922-7846-1|author=Kostyal, K.M.; White, Mel; Walker, Paul Robert; Heacox, Kim}}
*{{cite book|last=McNeese|first=Tim|title=The Missouri River|publisher=Infobase Publishing|year=2004|isbn=0-7910-7724-1}}

==External links==
{{commons category|Missouri River}}
{{Wikisource}}
*[http://www.cerc.usgs.gov/ScienceTopics.aspx?ScienceTopicId=10 USGS Columbia Environmental Research Center: Missouri River]
*[http://www.mappingsupport.com/p/gmap4.php?q=https://sites.google.com/site/gmap4files/p/news/missouri_river.txt&label=onq=https://sites.google.com/site/gmap4files/p/news/missouri_river.txt&label=on Interactive Maps and Air photos for Missouri River Dams and Reservoirs]
*[http://www.helenahistory.org/dams.htm Missouri River Dams: Canyon Ferry, Hauser and Holter Dams]
*{{osmrelation-inline|1756890|bullet=no}}

{{Missouri River}}
{{United States topics}}
{{Protected Areas of Montana}}
{{MissouriRiverDams}}
{{Fur Trade in Nebraska}}

{{good article}}

[[Category:Missouri River| ]]
[[Category:Borders of Iowa]]
[[Category:Borders of Kansas]]
[[Category:Borders of Missouri]]
[[Category:Borders of Nebraska]]
[[Category:Borders of South Dakota]]
[[Category:Geography of Omaha, Nebraska]]
[[Category:Geography of Yankton County, South Dakota]]
[[Category:Landforms of Gallatin County, Montana]]
[[Category:Landforms of Broadwater County, Montana]]
[[Category:Landforms of Lewis and Clark County, Montana]]
[[Category:Landforms of Cascade County, Montana]]
[[Category:Landforms of McCone County, Montana]]
[[Category:Landforms of Roosevelt County, Montana]]
[[Category:Rivers of Iowa]]
[[Category:Rivers of Kansas]]
[[Category:Rivers of Missouri]]
[[Category:Rivers of Montana]]
[[Category:Rivers of Nebraska]]
[[Category:Rivers of North Dakota]]
[[Category:Rivers of South Dakota]]
[[Category:Tributaries of the Mississippi River]]
[[Category:Waterways in Omaha, Nebraska]]

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