Which 1804–1806 expedition explored the newly acquired Louisiana Territory and reached the Pacific Ocean?

The Lewis and Clark Expedition explored the newly acquired Louisiana Territory and reached the Pacific Ocean from 1804 to 1806.

President Thomas Jefferson commissioned Meriwether Lewis and William Clark after the Louisiana Purchase. Their official mission was to map the new territory, study its plants and animals, and seek a practical route across the continent.

The Corps of Discovery left near St. Louis in May 1804. The party traveled up the Missouri River, crossed the Rocky Mountains, and reached the Pacific coast in November 1805 before returning east.

The expedition depended on Indigenous knowledge and assistance. Sacagawea, a Lemhi Shoshone woman traveling with the group, helped with communication and travel, while her presence and that of her infant son signaled peaceful intentions to some communities.