After Thomas Jefferson doubled the size of the United States with the Louisiana Purchase in 1803, he assembled an expedition to explore this vast territory. Leading the expedition were two former army captains -- Meriwether Lewis and William Clark.
Braving unfamiliar territory and dangerous conditions for more than two years, Lewis and Clark successfully crossed the entire western United States, mapping the territory and discovering its resources. Retrace the route that changed our understanding of the continent in this interactive Google Earth Voyager story.
Learn more about the lives and journeys of some of history's greatest explorers with our PBS World Explorers collection.