What expedition, led by Meriwether Lewis and William Clark, 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 after the United States acquired Louisiana from France. Meriwether Lewis and William Clark jointly led the Corps of Discovery, which traveled up the Missouri River, crossed the Rocky Mountains, reached the Pacific Ocean, and returned to the Mississippi Valley.

The expedition departed from Camp Dubois near St. Louis on May 14, 1804, and returned in September 1806. Its members mapped routes, recorded plants and animals, gathered geographic information, and established diplomatic contacts with many Indigenous nations. Sacagawea traveled with the group and assisted with communication and navigation.

The expedition did not “discover” an unknown wilderness: Indigenous peoples already lived throughout the region, and European powers had explored parts of it earlier. Its importance lies in the detailed information it supplied to the expanding United States and the political claims that followed.