Personally selected by President Thomas Jefferson, Captain Meriwether Lewis was assigned to lead an expedition to the West, where the United States had just completed the Louisiana Purchase land transaction with France. Lewis selected William Clark to accompany him, and as leaders of the Corps of Discovery, the men became the first to find an overland route to the Pacific Ocean, the first to travel on the Missouri River in the future state of Montana, the first to cross the Continental Divide south of Canada, and the first white men to make direct contact with the Shoshone, the Flathead, and the Nez Perce Indians. Perhaps most importantly, Lewis and Clark discovered and described 122 species of Western birds and animals and 178 plants. Their 200,000-word journals continue to be a source of fascination to Americans. In ""Lewis and Clark"", read how these two adventurers are still celebrated as among the greatest of American explorers.
Samuel Willard Crompton has contributed sections on explorers and exploration to a number of works, including the American National Biography and the Atlas of Exploration. Crompton teaches history at Westfield State College and Holyoke Community College.