Lewis and Clark Expedition

(1804–1806)

   The first overland expedition of discovery across the United States to the Pacific Ocean and back, mandated by President Thomas Jefferson as the Corps of Discovery, following the Louisiana Purchase. Serving as the private secretary of President Jefferson, Meriwether Lewis (1774–1809) was selected by Jefferson in 1803 to lead the expedition. Accompanying Lewis was Second Lieutenant William Clark (1770–1838) of the United States Army, a veteran of many Indian wars. They were instructed to forge business relations with tribes they encountered in the West. The president also asked them to record the plants, animals, minerals, and geography they encountered and in particular to determine whether there existed a transcontinental water route for westward expansion. Jefferson was concerned about establishing an American presence in the West, as British and Canadian trappers had made inroads there.

   Lewis and Clark, accompanied by approximately 50 men, spent the winter of 1803 in the St. Louis area. In the spring of 1804, they sailed up the Missouri River. In the winter they made it to what is now the Dakotas, and they camped among the Mandan Indian tribe. Early in 1805, they set out to cross the West. They were accompanied by Sacajawea, a Shoshone Indian woman who guided them across the Rockies. In November 1805, the party finally reached the Pacific Ocean. In July 1806, the expedition split into two groups, Lewis and his team turning back through Blackfoot territory while Clark returned through Crow territory. They eventually rejoined in present-day North Dakota where the Yellowstone River flows into the Missouri and arrived in St. Louis in September. Their explorations resulted in establishing relations with many Western tribes; discovering passages through the Rockies; and providing important botanical, zoological, and geological information about much of the West. The expedition was instrumental in opening the trans-Mississippi region to white settlement. In 1807, Jefferson appointed Lewis governor of the Louisiana Territory. Clark became the first governor of the Missouri Territory in 1813.

   See also <>.

   FURTHER READING:

    Ambrose, Stephen E. Undaunted Courage: Meriwether Lewis, Thomas Jefferson, and the Opening of the American West. New York: Simon & Schuster, 1996;

    Dillon, Richard H. Meriwether Lewis: A Biography. Santa Cruz, CA: Western Tanager Press, 1988;

    Raum, Elizabeth. Meriwether Lewis. Chicago: Heinemann Library, 2004.

   GENE C. GERARD