Which expedition explored the Louisiana Purchase from 1804 to 1806?

The Lewis and Clark Expedition explored the Louisiana Purchase from 1804 to 1806. President Thomas Jefferson selected Meriwether Lewis and William Clark to lead the Corps of Discovery across the newly acquired territory.

The expedition began near St. Louis in May 1804 and traveled up the Missouri River, crossed the Rocky Mountains, and followed the Columbia River to the Pacific Ocean. The group returned to St. Louis in September 1806 after covering thousands of miles.

The expedition mapped routes, recorded plants and animals, and gathered information about geography and Native nations. Sacagawea, a Lemhi Shoshone woman, traveled with the party and assisted with communication and travel, particularly during the crossing of the northern Rocky Mountains.

The journey did not mean the region was uninhabited or unknown. Indigenous nations had lived across the territory for generations and provided essential knowledge, supplies, and guidance. Lewis and Clark’s records expanded United States knowledge from an American governmental perspective, but the expedition also formed part of a broader process of territorial expansion.