Missouri-Yellowstone Confluence Interpretive Center
... this long wished for spot
— Meriwether Lewis
For many generations, Native peoples came from all directions for the abundant bison and other game, using only seasonal settlements in order to follow migrating herds. As a result this area was significant for both intertribal trade and hostilities.
During their winter at Fort Mandan, Lewis and Clark heard much about the Yellowstone River and its confluence with the Missouri River from native hunters. The American Fur Company built Fort Union Trading Post, at a place commended by Clark, to serve the Assiniboine and other Northern Plains tribes. For much of its long history (1828-1867), it served as the westernmost port for shipping furs by steamboat to the East.
Both rivers remain important for the snowmelt they carry from the Rocky Mountains into the arid Great Plains. Today, the Army Corp of Engineers manages flow of the Missouri River from six major reservoirs to supply water for downstream needs. The Yellowstone River, in contrast, remains the largest free-flowing river in the country.
I ascended the hills from whence I had a most pleasing view of the country, perticularlly of the wide and fertile vallies formed by the missouri and the yellowstone rivers, which occasionally unmasked by the wood on their borders disclose their meandering
for many miles in their passage through these delightfull tracts of country. I could not discover the junction of the rivers immediately, they being concealed by the woods....the whol face of the country was covered with herds of Buffaloe, Elk & Antelopes; deer are also abundant....
— Meriwether Lewis, Thursday April 25 1805
Mr. Hamilton (an Englishman who has lived here several years), some company clerks, and numerous, engages as well as other from all nations - Americans, Englishmen, Frenchmen, Germans, Russians, Spaniards, and Italians - about one hundred of them, (were) assembled here.
— Prince Maximilian, on his arrival at Fort Union Trading Post, 24 June 1833