U.S. Route 136 (US 136) runs east–west across central Illinois for 225.5 miles (362.9 km). US 136 enters the state from Iowa across the Keokuk–Hamilton Bridge over the Mississippi River between Keokuk, Iowa, and Hamilton, Illinois, and exits into Indiana east of Danville. The largest population centers along the route are Macomb, Rantoul, and Danville.

Illinois Route 336 is a four-lane freeway/expressway combination that serves western Illinois. It is also used by the Illinois Department of Transportation (IDOT) as a part of Federal-Aid Primary Highway 315 (FAP315) to refer to a future project connecting the cities of Quincy and Peoria via underserved Macomb.