Cahokia is a village in St. Clair County, Illinois, United States. It is part of Greater St. Louis, the metropolitan area around St. Louis. As of the 2010 census, the village had a population of 15,241, a decline from 16,391 in 2000. The name is a reference to one of the clans of the historic Illini confederacy, who were encountered by early French explorers to the region.
Early European settlers also named Cahokia Mounds after the Illini. This is an extensive prehistoric Mississippian culture urban complex located to the north in present-day Collinsville in Madison County. It is a UNESCO World Heritage Site and a State Historic Park.
The village of Cahokia is the home of significant colonial and Federal-period buildings listed on the National Register of Historic Places: the Cahokia Courthouse (c 1740), in the French Colonial style, Church of the Holy Family (Cahokia) (c. 1697), and the Jarrot Mansion (c 1810).