This book is the first to situate the Lewis and Clark expedition within the political and scientific ambitions of Thomas Jefferson. It spans a forty-year period in American history, from 1783-1832, covering Jefferson\'s early interest in trying to organize an expedition to explore the American West through the difficult negotiations of the Louisiana Purchase, the formation of the "Corps of Discovery," the expedition\'s incredible journey into the unknown, and its aftermath. The story of the expedition is told not just through the journals and letters of Lewis and Clark, but also through the firsthand accounts of the expedition\'s other members, which included Sacagawea, a Native American woman, and York, an African American slave. The book features more than 100 primary source documents, including letters to and from Jefferson, Benjamin Rush, and others as the expedition was being organized; diary excerpts during the expedition; and, uniquely, letters documenting the lives of Lewis, Clark, Sacagawea, and York after the expedition.