Cahokia is a village in St. Clair County, Illinois, United States. As of the 2000 census, the village had a population of 16,391. The name is a reference to Cahokia Mounds, a Native American city near Collinsville, Illinois. Cahokia is the home of the Cahokia Courthouse and the Jarrot Mansion. Cahokia apartments for rent comparison page shows most up to date rent information on Cahokia apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.