What impact did the Lewis and Clark expedition have on developing the United States west of the Mississippi River?
The Lewis and Clark Expedition had an enormous impact on American westward expansion. Arguments have been advanced that President Jefferson’s dispatch of his personal secretary, Meriwether Lewis, along with Captain William Clark, a noted explorer and soldier, on a journey to observe, note, and map the vast territories beyond the Mississippi River was motivated more by the president’s need to better understand the state of the US Army at its outermost stations. However, Lewis’s participation in the journey to the Pacific provided such a wealth of detail about virtually every facet of geography and nature that the subsequent mass migration of Americans westward was rendered considerably more viable. The expedition named for these two men produced voluminous data on many things either previously unseen or undocumented (by European and/or American eyes) that warrants continued attention today. Note in the following passage from Lewis’s journals his description of just one particular type of bird:
The Black woodpecker which I have frequently mentioned and which is found in most parts of the roky Mountains as well as the Western and S. W. mountains, I had never an opportunity of examining until a few days since when we killed and preserved several of them. this bird is about the size of the lark woodpecker or the turtle dove, tho' it's wings are longer than either of those birds. the beak is black, one inch long, reather wide at the base, somewhat curved, and sharply pointed; the chaps are of equal length. around the base of the beak including the eye and a small part of the throat is of a fine crimson red.
This is one paragraph in the thousands of pages of notes, illustrations and maps produced by Lewis and Clark during their two-year journey. Lewis’s description of the “black woodpecker” is not an anomaly; it is, rather, illustrative of the journals’ contents. Notes from May 8, 1806 provide useful insights on the types of wild game available for sustenance:
by 11 A.M. all our hunters returned, Drewyer and Cruzatte brought each a deer, Collins wounded another which my dog caught at a little distance from the camp. our stock of provision now consisted of 4 deer and the remnant of the horse which we killed at Colter's Creek. Sheilds killed a duck of an uncommon kind. the head beak and wing of which I preserved.
The journals of Lewis and Clark are an invaluable historical record. Their contemporaneous use by Jefferson and others were instrumental in convincing leaders of the young nation that the territories beyond the Mississippi were worth further exploration and, as importantly, further occupation. That Jefferson fully intended the expedition to provide the kinds of information essential for future settlement is evident in the instructions he provided the two officers before their departure. In his letter to Lewis detailing the types of information he wanted collected, Jefferson included the following passage:
And considering the interest which every nation has in extending & strengthening the authority of reason & justice among the people around them, it will be useful to acquire what knolege you can of the state of morality, religion & information among them, as it may better enable those who endeavor to civilize & instruct them, to adapt their measures to the existing notions & practises of those on whom they are to operate.
That is an informative instruction from the president to his emissary to the uncharted territories beyond the then-existing borders of the United States. It strongly suggests an interest in establishing a long-term presence in those territories.
The main effect of the Lewis and Clark Expedition was to stimulate interest in the region west of the Mississippi. Their descriptions of the fauna of the region in particular piqued the interest of fur traders, who poured into the Rocky Mountains and the Pacific Northwest in droves in the twenty or so years following the expedition. Of course, the interests of fur-trading companies were also furthered by the Louisiana Purchase, which gave the United States possession of most of the region explored by the expedition. Their exploration efforts also enabled the United States to claim the disputed Pacific Northwest, as Lewis and Clark had been to the Pacific Ocean. Possession of the region was finally settled in the 1840s. The fact that all of these developments were disastrous for Indian peoples along their route—from the Mandan along the Missouri to the Nez Perce in the Pacific Northwest—should go without saying. But the Lewis and Clark Expedition was very important in promoting the growth and development of the United States in the trans-Mississippi West.
Besides simply giving us a journal to follow which described what we would find out West in terms of flora and fauna (plants and animals), but helped us to know which Native tribes were friendly and which were hostile, what the safest routes were and simply the fact that it was possible to reach the West overland and live to tell the tale was something they contributed.
By exploring the Pacific Northwest, they also inadvertently claimed it for the United States, which led to increased settlement later, especially in present day Oregon through the Oregon Trail.
Prior to Lewis and Clark's journey, the American West was largely unexplored and unknown. Their encounter with Sacajewea and their findings along their route would serve as the basis for eventual westward expansion and Americans' newfound fascination with homesteading west of the Mississippi River.
Without the voyages of Lewis and Clark, the United States might have remained unaware about life and land in the western half of our country, and the displacement of Native Americans there might never have occurred.