Ohio River course forms the northern borders of West Virginia and Kentucky; and the southern borders of Ohio, Indiana and Illinois, until it joins the Mississippi River at the city of Cairo, Illinois. Where the Ohio joins the Mississippi is the lowest elevation in the state of Illinois, at . The Ohio River, which flows westward from Pittsburgh, Pennsylvania, to Cairo, Illinois, is the largest tributary, by volume, of the Mississippi River in the United States. At the confluence, the Ohio is considerably bigger than the Mississippi. Measured by long-term mean discharge in cubic feet per second and cubic meters per second,
Embarras River (Illinois) southeastern Champaign; the southern portion of the University of Illinois campus, including the small creek near the Vet Med Building; and Meadowbrook Park in south Urbana. The Embarras flows generally southward through Douglas, Coles, Cumberland, and Jasper Counties. In Jasper County, it turns southeast for the remainder of its course through Richland, Crawford, and Lawrence Counties. Portions of the river's lower course have been straightened and channelized. It joins the Wabash River southwest of Vincennes, Indiana. Along its course, the Embarras passes the towns of Villa Grove, Camargo, Charleston, Greenup, Newton, Ste. Marie, and Lawrenceville. The United States Board on