Answer:
It is difficult to overstate the long-term ramifications of the Expedition. The most noticeable immediate effect was the rise in the northern plains fur trade between 1806 & 1812. During that period individuals like Manuel Lisa & John Colter–the latter a member of the Corps of Discovery–established short-lived trade from northern South Dakota to Montana. After the War of 1812, the trade was renewed with the advent of the Mountain Man period (1820- 1845), during which time additional posts were erected in the region. Ft. Union was perhaps the flagship of these interests, particularly for its owners, the American Fur Company of St. Louis.
Artists quickly followed in the wake of the Expedition, with individuals such as Charles St. Memin, Paul Kane, George Catlin, & Karl Bodmer presenting to the world startling images of life on the Northern Plains. These helped to further popularize the west in the popular imagination & would help fuel immigration in the decades to come.
For Native Peoples, the aftermath of the Lewis and Clark was anything but a positive experience. Perhaps the most devastating was the outbreak of smallpox among the Mandan in 1837, an epidemic which all but destroyed the once-powerful group. This catastrophe was a major impetus in further uniting the surviving Mandan & Hidatsa, whom the Arikara joined at Like-A-Fish-Hook village. There the Three Affiliated Tribes engaged in trade, farming, & hunting. Worst of all, during the last quarter of the 19th century, the reservation system was instituted, taking away from the original inhabitants the vast majority of their land. On reservations like Ft. Berthold, residents were forced to convert to Christianity, take up farming in place of hunting, & educate their children in white boarding schools. This terrible pattern was repeated across the trans-Mississippi west and took a devastating toll on all tribes involved.
The military also made its presence known by the mid-to late-19th century, eventually building a series of forts across North Dakota in an effort to protect settlers & railroad workers. Ft. McKeen, Ft. Abraham Lincoln, Ft. Rice, Ft. Yates, Ft. Totten, Ft. Abercrombie, Ft. Buford, Ft. Berthold, & Ft. Pembina were among the most notable of these military posts. Some of these forts were the site of later historic events, such as Chief Joseph & Sitting Bull’s giving up their struggle against white incursion on their lands and forced culture change.
Economic, political, military, & social forces brought to bear as a result of the expedition forever changed the northern plains that the Native Peoples had known, & would also forever change those who came to the prairie.
