What expedition sent by Thomas Jefferson explored the Louisiana Purchase from 1804 to 1806?

The Lewis and Clark Expedition explored the Louisiana Purchase from 1804 to 1806.

President Thomas Jefferson commissioned the expedition soon after the United States acquired the Louisiana Territory from France in 1803. Meriwether Lewis and William Clark led the Corps of Discovery, which included soldiers, boatmen, interpreters, and York, an enslaved man owned by Clark. Sacagawea joined the group with her infant son and helped the expedition communicate and travel.

The expedition left the St. Louis area in May 1804, followed the Missouri River, crossed the Rocky Mountains, and reached the Pacific Ocean near present-day Oregon in November 1805. The explorers returned to St. Louis in September 1806 after traveling thousands of miles.

Its goals included mapping the new territory, studying plants and animals, finding transportation routes, and establishing relations with Native nations. The expedition did not discover a practical all-water route across the continent, but its maps and reports greatly expanded U.S. knowledge of the West.