Crow Agency, Montana

According to the United States Census Bureau, the CDP has a total area of {{convert|7.3|sqmi|km2}}, all of it land.

The Treaty of Fort Laramie of 1851 created extensive reservation lands for the Indian tribes in Montana, Wyoming and the Dakotas at a time when the non-Indian presence in this area was limited to roving traders.  A large reservation for the Crow Tribe was set out that was centered on the Big Horn Mountains and extended eastward into the Powder River basin to the banks of the Powder River.<ref>{{cite web|title=TREATY OF FORT LARAMIE, 1851.|url=http://digital.library.okstate.edu/kappler/Vol2/treaties/sio0594.htm|publisher=Compiled and edited by Charles J. Kappler. Washington : Government Printing Office, 1904.|accessdate=4 October 2013}} Article 5 describes the Crow lands as follows: "The territory of the Crow Nation, commencing at the mouth of Powder River on the Yellowstone; thence up Powder River to its source; thence along the main range of the Black Hills and Wind River Mountains to the head-waters of the Yellowstone River; thence down the Yellowstone River to the mouth of Twenty-five Yard Creek; thence to the head waters of the Muscle-shell River; thence down the Muscle-shell River to its mouth; thence to the head-waters of Big Dry Creek, and thence to its mouth."</ref>  However, this treaty did not indicate agency sites for any of the tribes, including the Crows. At the time of the treaty, 1851 the Crow tribe consisted of nomadic bands whose culture was based on hunting the migratory buffalo herds, including those herds in the Powder River Country.  Hunting in the Powder River area on the east side of the Big Horn Mountains brought the Crow in increasing conflict with more powerful bands of Sioux who were migrating westward.  In 1863 gold was discovered in commercial quantities in the mountains of the western Montana Territory.  Travelers to the gold fields left the Oregon Trail and traveled through the Powder River country, going up the east side of the Big Horns to the Yellowstone valley, and then westward.  This route became known as the Bozeman Trail, and three forts were built to protect travelers.  The Sioux conducted an all out war against the forts and the travelers on the Bozeman Trail called "Red Cloud's War", which finally forced the United States to agree to abandon the forts, and close the trail, and to remake the boundaries of the reservations for the Crow and Sioux in the Fort Laramie Treaty of 1868.

The 9-year period from 1875 to 1884 was a time of rapid transition on the plains of eastern Montana and Wyoming.  In 1876 the Crows provided scouts for the United States military forces in the [[Great Sioux War of 1876]].  The defeat by the Sioux of [[Custer|George Armstrong Custer]] at the [[Battle of the Little Big Horn]] in 1876 resulted in a concerted military backlash against the Sioux, and by 1877 and 1878 the hostile bands of Sioux had either fled to Canada, or they had surrendered and were confined to reservations along the Missouri River in the Dakotas. This initially left the Crows more secure in their use of the buffalo ranges on the eastern Montana and Wyoming plains, but in 1876 and 1877 federal forts were built across this area.  With hostile Indian presence essentially neutralized, hide hunters came to harvest the northern buffalo herds. By 1882 the buffalo were gone from this area.  Also, in 1880 the Northern Pacific Railroad began building eastward from Bismark, ND, and in 1882 they completed their northern transcontinental line, which passed up the Yellowstone River valley just as the last of the buffalo disappeared.  Almost at once large Texas trail herds arrived in the Montana Territory to exploit the now empty open range on the vast plains of central and eastern  Montana.  These successive rapid changes in this 9-year period eliminated the herds of bison and reduced other wild game on which the Crow culture relied, and ended forever the Crow's nomadic way of life.