During their expedition with the Corps of Discovery, Meriwether Lewis and William Clark traveled approximately 3,700 miles from the city of St. Louis to the Pacific Ocean. The expedition left St. Louis on May 14, 1804, and continued for 18 months, concluding at the Pacific Ocean in November 1805.
Lewis, Clark and the Corps of Discovery did not head back to St. Louis until March 23, 1806. The return trip to St. Louis took approximately six months, giving the expedition a total travel time of two years, four months and 10 days. Of the 59 people who travelled with the Corps of Discovery during its journey, only one person died during the trip.