Lewis and Clark led the first US expedition to the Pacific Coast from 1804 to 1806 as directed by President Thomas Jefferson. Their main objectives were to study the regions' geography, plants, animals, and native peoples along the Missouri River, and to establish trade and assert US sovereignty. Though they did not discover an all-water route to the Pacific, they succeeded in their mission by cataloging hundreds of new species, mapping the terrain, and fostering better relations with indigenous groups.