The Lewis and Clark National Historic Trail , some 3 @,@ 700 miles ( 6 @,@ 000 km ) long , follow nearly the entire Missouri River from its mouth to its source , retracing the route of the Lewis and Clark Expedition . Extending from Wood River , Illinois , in the east , to Astoria , Oregon , in the west , it also follow portions of the Mississippi and Columbia Rivers . The trail , which span through eleven U.S. states , is maintained by various federal and state government agencies ; it pass through some 100 historic sites , notably archaeological locations including the Knife River Indian Villages National Historic Site .