[8] The Mandan Indians knew of cataracts and called them by a descriptive (but not formal) name: Minni-Soze-Tanka-Kun-Ya,[9] or "the great falls.

[2][10] "Beautiful Cascade" was renamed "Rainbow Falls" in 1872 by Thomas B. Rogers, an engineer with the Great Northern Railway.

[19][21] Between 15,000 and 11,000 BCE, the Laurentide Ice Sheet blocked the Missouri River and created Glacial Lake Great Falls.

[23] The current course of the Missouri River essentially marks the southern boundary of the Laurentide Ice Sheet.

[24] The Missouri, Yellowstone and Musselshell rivers flowed eastward around the glacial mass, eventually settling into their present courses.

[26] The Missouri River settled into a bedrock canyon which lay beneath the clay laid down by Glacial Lake Great Falls.

Until relatively recently (in geologic time) the Missouri River in the area had a much wider channel,[32] but it has now settled into its current course, where it will continue to cut more deeply into the sandstone.

[23][33] The earliest inhabitants of North America entered Montana east of the Continental Divide between the Cordilleran and Laurentide ice sheets.

[35] Salish Indians would often hunt bison in the area on a seasonal basis, but no permanent settlements existed near the Great Falls for much of prehistory.

[35] The Great Falls of the Missouri remained in the tribal territory of the Blackfeet until Americans claimed the region in 1803.

[37] On May 14, 1804, the Lewis and Clark Expedition departed St. Louis, Missouri to map the course of the Missouri River; establish whether a river route to the Pacific Ocean existed; study the Indian tribes, botany, geology, terrain and wildlife in the region; and evaluate whether British and French Canadian hunters and trappers in the area posed a challenge to American control over the region.

[2][40] At the final waterfalls, Lewis saw an amazing sight:[38] Mounting a hill near Black Eagle Falls (probably where the town of Black Eagle is today), Lewis saw that the cataracts ended and that another large river joined the Missouri about two and a half miles further upstream.

Lewis and nine men stopped at the Great Falls with the intention of exploring the Marias River and discovering its source.

[48] Following the return passage of Lewis and Clark in 1805/06 there is no record of any white man visiting the Great Falls of the Missouri until explorer and trapper Jim Bridger reached them in 1822.

[12] White people next visited the Great Falls when Bridger and Major Andrew Henry led a fur-trading expedition there in April 1823 (and were attacked by Blackfeet Indians while camping at the site).

[59][60][61][62] He returned in 1883 with surveyors and platted a city (to be named Great Falls) on the south side of the river.

[12] With investments from railroad owner James J. Hill and Helena businessman C. A. Broadwater, houses, a store, and a flour mill were established in 1884.

[69] The Lewis and Clark National Historic Trail Interpretive Center was built in 1998 on a cliff overlooking the Missouri River near Crooked Falls.

It provides an extensive look into Lewis and Clark's discovery of the Great Falls and their portage around them, as well as exhibits on native peoples of the area.

[2] In 1807, Lewis commissioned the Irish engraver John James Barrelet to make drawings of the Great Falls.

The waterfalls may be seen in the background of John Mix Stanley's large painting "Barter for a Bride" (originally titled "A Family Group"), which was painted some time between 1854 and 1863 and now hangs in the Diplomatic Reception Room in the United States Department of State in Washington, D.C.[72] The noted Western painter O. C. Seltzer depicted the cataracts in his 1927 work, "Lewis and Clark With Sacajawea at the Great Falls of the Missouri, 1804.