Lewis and Clark Set Out
The Corps of Discovery departed to explore and map the newly acquired western territories
May 14, 1804
Exploring an Unknown Continent
In May 1804, Meriwether Lewis and William Clark set off from Camp Dubois near St. Louis, Missouri, with a group of about 33 people known as the Corps of Discovery. Their mission, assigned by President Thomas Jefferson, was to explore the territory acquired in the Louisiana Purchase of 1803 and find a practical route to the Pacific Ocean. Jefferson also wanted them to document the geography, plants, animals, and native peoples of the region — land that was largely unknown to Americans, though it had been home to Native nations for thousands of years. The journey would cover more than 8,000 miles round trip and take more than two years.
Sacagawea and the Route West
One of the most important members of the expedition was Sacagawea, a young Shoshone woman who joined the group during the winter of 1804–1805 along with her French-Canadian fur trader husband. She served as an interpreter and guide through territory she knew, and her presence — traveling with an infant son — signaled to other Native nations that the expedition was peaceful. The Shoshone were essential for obtaining the horses the Corps needed to cross the Rocky Mountains. Sacagawea guided the party through terrain that would have been nearly impassable without her knowledge. She remains one of the most recognized and celebrated figures in American history.
What They Found and What Followed
Lewis and Clark reached the Pacific Ocean in November 1805 and returned to St. Louis in September 1806. They brought back journals filled with descriptions of hundreds of plant and animal species new to science, detailed maps of the western territories, and accounts of the many Native nations they had encountered. Only one member of the expedition died during the journey, from a medical condition. The expedition opened the way for American expansion into the West, which ultimately brought enormous suffering to Native peoples through displacement, broken treaties, and violence. The Lewis and Clark expedition is a landmark in American exploration and a pivotal moment in the story of westward expansion.