Illinois Route 40 is a 112.05-mile-long (180.33 km) north–south route in central portion of the U.S. state of Illinois. It runs from Interstate 74 (I-74) in East Peoria north to IL 78 at Mt. Carroll, just south of U.S. Route 52 and IL 64.

East Peoria is a city in Tazewell County, Illinois, United States. The population was 22,484 at the 2020 census. East Peoria is a suburb of Peoria and is part of the Peoria, Illinois Metropolitan Statistical Area, located across the Illinois River from downtown Peoria. It is home to many Caterpillar Inc. facilities.