Written accounts and archaeological finds show that Native Americans inhabited the Creve Coeur area from 9500 B.C. to 1800 A.D. French explorers began farming and fishing in the area in the early 18th century, and fur trappers settled there in the early 19th century. When the area was acquired by the United States through the Louisiana Purchase in 1803, the Lewis and Clark Expedition came through Creve Coeur. During the American Civil War, men from the area served on both sides of the conflict, but most residents were southern sympathizers.