Which 1804 expedition explored the newly acquired Louisiana territory for President Thomas Jefferson?

The Lewis and Clark Expedition explored the newly acquired Louisiana territory for President Thomas Jefferson.

The expedition officially began on May 14, 1804, when the Corps of Discovery left Camp Wood near present-day St. Charles, Missouri. Jefferson selected Meriwether Lewis to lead the project, and Lewis chose William Clark as co-leader. Their instructions included mapping waterways, documenting geography and plants, and establishing diplomatic relationships with Indigenous nations.

The party traveled up the Missouri River, crossed the Rocky Mountains, and reached the Pacific Ocean in November 1805. It returned to St. Louis in September 1806 after covering thousands of miles. Sacagawea, a Lemhi Shoshone woman, accompanied the expedition with her infant son and contributed knowledge and assistance during parts of the journey.

The expedition did not discover an unknown continent or prove that a water route crossed North America; Europeans and Indigenous peoples already knew much of the region. Its major achievement was gathering information that helped the United States understand and claim knowledge of its new western lands.