Lewis and Clark

Meriwether Lewis and William Clark, leaders of the Corps of Discovery (1804-1806) — Jefferson's expedition to map and document the territory acquired in the Louisiana Purchase.

The first overland crossing of North America by Americans: the Corps of Discovery documented the geography, flora, fauna, and indigenous peoples of the American West with scientific rigor. Jefferson's political purpose (establishing American claim to the Pacific Northwest) was combined with genuine natural history research. The expedition's journals are the foundational document of American westward expansion. Sacagawea's role (Shoshone interpreter and guide) is now recognized as essential rather than incidental. The expedition's structure — civilian volunteers crossing 8,000 miles over 28 months — is a case study in expedition organization and leadership under sustained hardship.