Which expedition explored much of the Louisiana Purchase after the United States acquired it?

The Lewis and Clark Expedition explored much of the Louisiana Purchase after the United States acquired it.

President Thomas Jefferson commissioned Meriwether Lewis and William Clark to lead the expedition in 1803. The Corps of Discovery departed from Camp Dubois near St. Louis in May 1804, traveled up the Missouri River, crossed the Rocky Mountains, and reached the Pacific Ocean. The explorers 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 journey with her infant son and helped the group communicate and navigate. Toussaint Charbonneau, her husband, also served as an interpreter.

The expedition did not explore every part of the Louisiana Purchase, nor did it discover lands unknown to Indigenous peoples. Its importance lies in providing the federal government with detailed information about a vast region and helping establish later U.S. claims and travel routes in the West.