The Ohio River flows 981 miles and begins where the Allegheny River and Monongahela River meet at Pittsburgh. The river flows southwestward, separting Ohio, Indiana and Illinois on the north from West Virginia and Kentucky on the south. It empties into the Mississippi River at Cairo, Illinois. Other large cities along the river include Wheeling WV, Cincinnati OH, Louisville KY and Evansville IN. The entire drainage is more than 200,000 square miles.