[209] In the months leading up to the expedition, Jefferson tutored Lewis in the sciences of mapping, botany, natural history, mineralogy, and astronomy and navigation, giving him unlimited access to his library at Monticello, which included the largest collection of books in the world on the subject of the geography and natural history of the North American continent, along with an impressive collection of maps.[210]
The expedition lasted from May 1804 to September 1806 (see timeline) and obtained a wealth of scientific and geographic knowledge, including knowledge of many Indian tribes.[211]

Other expeditions
Main articles: Dunbar–Hunter Expedition, Red River Expedition (1806), and Pike Expedition
In addition to the Corps of Discovery, Jefferson organized three other western expeditions: the William Dunbar and George Hunter Expedition on the Ouachita River (1804–1805), the Thomas Freeman and Peter Custis Expedition (1806) on the Red River, and the Zebulon Pike Expedition (1806–1807) into the Rocky Mountains and the Southwest. All three produced valuable information about the American frontier.[212]

Native American affairs
Main article: Thomas Jefferson and Native Americans
Black Hoof, leader of the Shawnee, accepted Jefferson's Indian assimilation policies.
