In 1801, the United States ended at the Mississippi River and almost all Americans lived 50 miles west of the Atlantic Ocean. When President Thomas Jefferson bought the Louisiana Territory from Napoleon, he doubled the country's size. The sudden western expansion of the United States--and rumors of a Northwest Passage that would link the Atlantic with the Pacific--motivated Jefferson to find the great byway to the West. Previously, it had been shrouded in mystery-- Jefferson's books described a world that contained erupting volcanoes, hills of pure salt and blue-eyed Indians who spoke Welsh. He appropriated $2,500 for the journey and commissioned his secretary, Meriwether Lewis, to the task of revealing the West. Lewis asked his old friend, William Clark, and a group of rough frontiersmen to join the expedition, now called the Corps of Discovery. This Ken Burns documentary chronicles the challenges, frustrations and anxiety that faced the Corps of Discovery -- their encounters with Nat