What was the name of the 1804–1806 expedition that explored the Louisiana Purchase and the Pacific Northwest?

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

President Thomas Jefferson selected Meriwether Lewis and William Clark to lead the expedition after the United States acquired the Louisiana Territory. Their official instructions included mapping rivers, studying plants and animals, documenting Indigenous nations, and seeking a practical route to the Pacific Ocean.

The Corps of Discovery departed near St. Louis in May 1804. The party traveled up the Missouri River, crossed the Rocky Mountains, followed the Clearwater and Columbia Rivers, and reached the Pacific coast in November 1805. It returned to St. Louis in September 1806.

The expedition did not discover an unknown continent. Indigenous peoples already lived throughout the regions it crossed, and the travelers relied on Native guides, interpreters, diplomacy, and trade. Sacagawea became one of the best-known members of the journey, although popular retellings sometimes exaggerate or simplify her role.