Lewis and Clark were sent by President Thomas Jefferson to explore the Louisiana Purchase territory and find a route to the Pacific Ocean. During their expedition from 1804 to 1806, they met Sacagawea, a Shoshone woman who served as an interpreter and guide. Though they hoped to find a river route, the Missouri River only went as far as present-day Montana, and the remaining journey was over land. In total, Lewis and Clark explored parts of seven modern U.S. states before reaching the Pacific coast in Oregon and returning east.