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,
Fox River (Little Wabash tributary) Fox River: Fox River (Little Wabash tributary) The Fox River is a tributary of the Little Wabash River in southern Illinois. It rises in Jasper County to the southeast of Newton and flows south past Olney, then joins the Little Wabash at the northeast corner of Edwards County, near Mt. Erie. The river is in length. There is a smaller "Fox River" that is a tributary of the Wabash River in southern Illinois, entering the Wabash near New Harmony, Indiana. The following cities, towns and villages are in the Fox River watershed: The following counties are at least partially drained