Illinois Route 13 is a major east–west state route in southern Illinois. Illinois 13 has its western terminus at Centreville at Illinois Route 157 and its eastern terminus at the Kentucky state line and the Ohio River, at Kentucky Route 56. This is a distance of 151.54 miles (243.88 km).

Illinois Route 157 (IL 157) is a 35.50-mile-long (57.13 km) north–south state highway in the southwestern part of the U.S. state of Illinois. The southern terminus of the highway is at an intersection with IL 3 in Cahokia. The northern terminus of the highway is at an intersection with IL 140 in Hamel.