Cahokia is a village now part of Cahokia Heights, Illinois, in St. Clair County, United States. It was founded as a colonial French mission in 1689. It is in Metro East, east of the Mississippi River in the Greater St. Louis metropolitan area. As of the 2020 census, Cahokia had a population of 12,096. On May 6, 2021, the village was incorporated into the new city of Cahokia Heights.