Lewis and Clark expedition Summary

  • Last updated on November 10, 2022

Acting as official representatives of the United States government, Lewis and Clark explored and charted territories newly acquired through the Louisiana Purchase. Their expedition helped spur westward movement by U.S. citizens who would eventually establish homesteads, cities, and businesses, taking advantage of the country’s abundant natural resources and connecting the far-flung parts of the nation through a series of roads and railways.

In 1803, when President Thomas Jefferson, ThomasJefferson issued detailed instructions to Meriwether Lewis, MeriwetherLewis for the conduct of an expedition up the Missouri River to the Pacific Ocean, he stated explicitly that the mission was “for the purposes of commerce.” Under this broad umbrella, Jefferson justified sending two army officers with a party of nearly thirty men called the Corps of Discovery on a two-year journey. The expedition would encounter dozens of Native American tribes already engaged in a brisk and complex trading system not only among themselves but also with traders representing the interests of the French and British governments.Lewis and Clark expeditionExploration;American Northwest

For some time, Jefferson had been worried about efforts by the British and French to establish claims to lands west and northwest of the Mississippi River, thereby threatening the security of the fledgling United States. In Jefferson’s view, security along the western border of the country would be better secured through trade than through warfare. He realized that to bring about commercial exchanges, the U.S. government would need sound knowledge of the landscape and its inhabitants. Hence, although the Louisiana Purchase was not completed until December, 1803, Jefferson began laying out to Congress the rationale for cross-continental exploration nearly a year earlier.

Lewis and his co-commander William Clark, WilliamClark were charged with documenting routes, specifically river passages, that might provide an unimpeded pathway from the Mississippi to the Pacific Ocean. Jefferson believed the population of his country would inevitably expand. The nation of farmers he envisioned would require additional land to thrive. He realized, however, that trade was key to the success of sophisticated agrarian communities, which would need to get goods to market and to obtain items they could not manufacture or grow locally.

Therefore, when Lewis began preparing for the expedition that eventually was launched in 1804, in addition to purchasing large quantities of weapons, ammunition, foodstuffs, medical supplies, and scientific equipment needed by his men, he spent about 30 percent of the funds allocated to him on sewing items, knives, and jewelry for the Native Americans the party would meet along the way. These goods were not specifically for trade, however; they were intended to show good faith toward the local tribes and to introduce them to materials Americans could provide in the future. Lewis and Clark also took along commemorative medals inscribed with a bust of Jefferson on one side and symbols of peace on the other to signal their intention of establishing friendly relationships with local tribes. The medals were also meant to make it clear that Lewis and Clark represented a government claiming sovereignty over the territory and wishing to engage in commerce with its new “citizens.”

During the two years in which Lewis and Clark traversed the continent westward to the Pacific Ocean and back again, they made it a point to meet peaceably with Native Americans;U.S. trade withNative American tribes, exchanging gifts and trading for foodstuffs and information that would help them locate the best routes to the west. Many tribes found their claim to be interested in trade rather curious, since these white men had little interest in fur pelts. Lewis and Clark knew, however, that, if they were successful, government officials would follow them later to establish trading posts all along the route they were mapping. When the explorers returned to the East in 1806, they provided information about potentially lucrative commercial opportunities and about the customs of tribes that might make good trading partners. Even before their journals were published in 1814, Americans had learned enough about their exploits to realize that there was great promise for trade and settlement west of the Mississippi.

The immediate result of the Corps of Discovery’s trek was an increase in activity by private traders operating out of St. Louis, which quickly became the hub for America’s dealings with Native American tribes west of the Mississippi. Only after the United States had obtained additional territory as a result of its war with Mexico in 1848 and gold was discovered in California was there wide-scale migration into the regions Lewis and Clark had traversed. Although their expedition had set the tenor for peaceful coexistence with Native Americans based on trade, subsequent actions by U.S. citizens and their government would instead be driven by a desire to remove indigenous peoples from locations that would be most beneficial to the white population for agriculture, mining, or manufacturing.

Further Reading
  • Ambrose, Stephen E. Undaunted Courage. New York: Simon & Schuster, 1996. Detailed account of the Lewis and Clark expedition, focusing on the hardships faced by the participants and their determination to carry out the mission assigned to them by President Jefferson.
  • Fritz, Harry William. The Lewis and Clark Expedition. Westport, Conn.: Greenwood Press, 2004. Useful handbook outlining the course of the expedition; provides brief biographies of principal participants and information on scientific and ethnographic contributions made by the party.
  • Hoxie, Frederick, and Jay Nelson, eds. Lewis and Clark and the Indian Country: The Native American Perspective. Urbana: University of Illinois Press, 2007. Collection of essays examining the impact of the expedition on Native Americans living in areas explored by Lewis and Clark; includes commentaries on matters of trade and commerce and a section discussing changes that occurred as a result of future incursions into the area by U.S. citizens.
  • Ronda, James. Jefferson’s West: A Journey with Lewis and Clark. Charlottesville, Va.: Thomas Jefferson Foundation, 2000. Brief account of Jefferson’s vision for the territories he sent Lewis and Clark to explore and of the realities the two leaders and their men discovered as they journeyed westward.
  • Seefeldt, Douglas, et al., eds. Across the Continent: Jefferson, Lewis and Clark, and the Making of America. Charlottesville: University Press of Virginia, 2005. Essays speculating on the impact of Lewis and Clark’s initial overtures to Native American tribes and commenting on the political and economic ramifications of the expedition for the development of the United States.


Fur trapping and trading

Indian removal

Louisiana Purchase

Native American trade

Pike’s western explorations

Categories: History