Which expedition explored much of the Louisiana Purchase beginning in 1804?

The Lewis and Clark Expedition explored much of the Louisiana Purchase beginning in 1804.

President Thomas Jefferson selected Meriwether Lewis and William Clark to lead the expedition after the United States acquired the territory from France. The Corps of Discovery Expedition left Camp Wood near present-day St. Charles, Missouri, on May 14, 1804.

The party traveled up the Missouri River, crossed the Rocky Mountains, and followed rivers to the Pacific Ocean. It reached the Pacific coast in November 1805 and returned to St. Louis in September 1806. The expedition mapped routes, recorded plants and animals, and gathered information about geography and Indigenous nations.

Sacagawea, a Lemhi Shoshone woman, joined the expedition with her husband Toussaint Charbonneau and helped communicate and navigate. The expedition did not “discover” an empty wilderness: numerous Indigenous nations already lived throughout the region. Its records expanded U.S. geographic knowledge and supported later travel and settlement.