Meriwether Lewis & William Clark lead the epic two year expedition which explored the vast territory of the Louisiana Purchase. The expedition started up the Missouri River travelling by keelboat and pirogue and ascended to the head of the Missouri. Crossing overland through the Rocky Mountains, they built canoes and conducted the first exploration of the Columbia River Valley, reaching the Pacific Ocean in the fall of 1805. The Lewis and Clark expedition navigated thousands of miles of uncharted water and prepared the first maps of this unknown area.