Illinois : Geographical Features

The topography of Illinois is mainly flat with hills in the northwest and on the fringes of the Ozark Plateau.

The highest natural point is Charles Mound at 1,235 ft (377 m) above sea level—far lower than Chicago's towering skyscrapers. The low point, at the extreme southern tip along the Mississippi River, is 279 ft (85 m) above sea level. Illinois has very poor drainage though it has more than 2,000 rivers and streams totaling 9,000 mi (14,500 km). The most important rivers are the Wabash and the Ohio, forming the southeastern and southern border. Other important rivers are the Mississippi, forming the western border; and the Illinois, flowing northeast–southwest across the central region. Lake Carlyle is the largest body of inland water.