Carterville is a city in Williamson County, Illinois, United States. At the 2020 census, the city's population was 5,848. The city is part of the Carbondale-Marion-Herrin combined statistical area and has grown considerably as a residential community of Carbondale and Marion. The city is located next to Crab Orchard National Wildlife Refuge. The Refuge's 44,000 acres of land and water contain a wide diversity of flora and fauna.