Lewis and Clark depart to explore the Northwest

On this day in US history, the Lewis and Clark expedition departs from St. Louis, Missouri, to begin their mission to explore the Northwest region from the Mississippi River to the Pacific Ocean on May 14, 1804. Even before the US government expanded into the Louisiana Purchase, President Thomas Jefferson ordered his private secretary, Meriwether Lewis, and William Clark to embark on an expedition with about 45 other men to the US Northwest, where they would return in September of 1806.