An amazing tale of discovery and exploration as National Geographic brings to life the first crossing of what would become the United States.

Meet Meriwether Lewis and William Clark and relive their historic expedition to explore the land from the Mississippi River to the Pacific Coast. Commissioned by President Thomas Jefferson after the Louisiana Purchase in 1803, the primary objective of Lewis and Clark's perilous journey was to explore and map the newly acquired territory, find a practical route across the Western half of the continent, and establish an American presence in this territory....