What was the name of the expedition that mapped the Louisiana Purchase from 1804 to 1806?

The Lewis and Clark Expedition mapped much of the Louisiana Purchase from 1804 to 1806.

President Thomas Jefferson commissioned Meriwether Lewis and William Clark to explore the new territory, find a practical route to the Pacific, and document its geography, plants, animals, and peoples. The Corps of Discovery departed near St. Louis in May 1804.

The party reached the Pacific Ocean in November 1805 and returned to St. Louis in September 1806. Sacagawea, a Lemhi Shoshone woman, assisted the expedition as an interpreter and guide, while her presence with a baby helped signal peaceful intentions.

The expedition did not “discover” an empty wilderness: Indigenous nations already lived across the region and provided crucial knowledge, supplies, and diplomatic assistance.