January 18, 1803
U.S. President Thomas Jefferson sends a secret message to Congress asking for approval and funding of an expedition to explore the Western part of the continent.
Meriwether Lewis begins his training as the expedition's leader in Philadelphia.
July 4, 1803
News of the Louisiana Purchase is announced; Lewis will now be exploring land largely owned by the United States.
In Pittsburgh, Lewis oversees construction of a keelboat, then picks up William Clark and other recruits as he travels down the Ohio River.
Lewis and Clark establish Camp Wood, the winter camp for their Corps of Discovery, on the Wood River in Illinois.