River, Illinois, U.S. Rising near Urbana, it flows southwest to enter the Mississippi River after a course of 320 mi (515 km).
The village of Kaskaskia, located near the junction of the river with the Mississippi, is near the site of a town founded by Jesuit missionaries in 1703. It was the capital of Illinois Territory (1809) and of the state (1818–20). It was severely damaged by floods several times.