Lewis and Clark expedition departs on the Ohio

Background. President Thomas Jefferson commissioned the Corps of Discovery in 1803 to explore the newly acquired territory following the Louisiana Purchase. Meriwether Lewis was named leader, and he invited William Clark to co-lead. Preparations began in Pittsburgh, where Lewis purchased a keelboat intended for the Missouri River ascent. The vessel was built to Lewis's specifications in the summer of 1803.

Preparations. Lewis studied medicinal cures in Philadelphia under Benjamin Rush in 1803. The keelboat for the first year of the journey was constructed near Pittsburgh, Pennsylvania, to Lewis's specifications. It was completed on August 31, 1803. Lewis purchased this vessel in Pittsburgh, which would later be used to ascend the Missouri River.

Departure. Lewis and his crew set sail from Pittsburgh on the afternoon of August 31, 1803. They traveled down the Ohio River to meet up with Clark near Louisville, Kentucky, in October 1803 at the Falls of the Ohio. Clark did not accompany this initial departure, as he set out from Camp Dubois in May 1804.