The Mandan were a sedentary agricultural people living in earth-lodge villages along the Missouri River in present-day North Dakota. The expedition built Fort Mandan near their villages and spent the winter of 1804-1805 among them — the longest the Corps stayed with any single people.
The Mandan villages were a great trade center of the Northern Plains, where goods from as far as the Pacific coast and Hudson Bay were exchanged. Their population was approximately 4,500 when the expedition arrived, though they had been severely reduced by earlier smallpox epidemics.
The Mandan provided food, shelter, and critical geographic information about the route ahead. Their detailed maps of the upper Missouri and its tributaries proved remarkably accurate. It was at the Mandan villages that Charbonneau and Sacagawea joined the expedition.
Chief Sheheke (Big White) later traveled to Washington, D.C. at the expedition’s invitation — a journey that would become an ordeal lasting three years due to Arikara hostility that prevented his return upriver. The Mandan suffered catastrophically from a smallpox epidemic in 1837 that reduced their population from approximately 1,600 to just 125 people.
