The Journals of Lewis and Clark

Meriwether Lewis and William Clark led the first United States expedition (1804–1806) to the Pacific Coast. Though Jefferson stated in one letter the goal was to find a "direct & practicable water communication across this continent, for the purposes of commerce" (the Northwest Passage), the expedition actually had several goals. In order to make a firm claim of “discovery” to the Pacific Northwest and compete with the British for control of land and the fur trade, Jefferson had the men follow the rivers, map them, and collect scientific data. Jefferson also placed special importance on declaring U.S. sovereignty over the tribes along the Missouri River and getting an accurate sense of the resources in the Louisiana Purchase.