History:

Lewis and Clark Expedition, first United States overland exploration of the American West and Pacific Northwest, beginning in May 1804 and ending in September 1806. The expedition was commissioned by President Thomas Jefferson and led by army officers Meriwether Lewis and William Clark. The exploration covered a total of about 13,000 km (about 8,000 mi), from a camp outside St. Louis to the Pacific Ocean and back. Like other scholars in his time, Jefferson believed in the existence of a Northwest Passage, or some kind of water connection between the Atlantic and Pacific oceans. The principal goal of the expedition was to locate such a route and survey its potential as a waterway for American westward expansion. Although Lewis and Clark did not find this route, the expedition succeeded in making peaceful contact with Native Americans and uncovering a wealth of knowledge about the peoples, geography, plants, and animals of the western United States.

Although Jefferson had long been interested in the American West, it was not until 1802 that he began to plan an expedition to the Pacific. After reading Voyages from Montréal (1801) by Canadian explorer and fur trader Sir Alexander Mackenzie in the summer of 1802, the president began to make preparations for an American expedition aimed at countering Mackenzie’s plans to make the West and Pacific Northwest part of the British Empire. Influenced by the renowned 18th-century journeys of Captain James Cook and Captain George Vancouver, Jefferson envisioned an official expedition that combined diplomatic, scientific, and commercial goals. He believed that the nation that dominated a water passage through the continent could control the destiny of all North America. He was also convinced that the West would be a paradise for American farmers.

The Corps of Discovery, as the expedition party was properly known, demanded more people than Jefferson first imagined. Before reaching their base camp at Wood River outside St. Louis, Lewis and Clark recruited a sizable number of civilian hunters, army soldiers, and French boatmen. While not all made the entire journey to the Pacific, some 48 men were part of the team when it left St. Louis heading up the Missouri River. The expedition roster included Clark’s slave, York, who some Native Americans called "Big Medicine," along with many other adventurers who came to play a major role in American expansion, such as the hunters John Colter and George Drouillard. Other members of the expedition who also kept journals were Sergeants Charles Floyd, Patrick Gass, and John Ordway, and Private Joseph Whitehouse. The Corps and its supplies went up the river on a large keelboat (a riverboat used for freight) and several smaller boats, requiring the experience of French boatmen.