St. Clair County is the ninth most populous county in Illinois, located in the southwestern part of the state along the Mississippi River bordering Missouri. Located directly east of St. Louis, the county is part of the Metro East region of the Greater St. Louis metropolitan area. As of the 2020 United States census, St. Clair County had a population of 257,400, making it the third most populous county in Illinois outside the Chicago metropolitan area. Belleville is the county’s seat and largest city.
Smithton is a village in St. Clair County, Illinois, United States. The population was 4,006 in the 2020 United States Census. It is part of the Metro East region of Greater Saint Louis.
Canteen Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 10,263 and it contained 4,027 housing units. Canteen Township was formed from Centreville Station Township when it was subdivided on March 5, 1910.
Caseyville Township is located in St. Clair County, Illinois, United States. As of the 2010 census, its population was 31,996 and it contained 14,054 housing units.
Centreville Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 25,386 and it contained 10,535 housing units. Centreville Township was formed from Centreville Station when it was subdivided on March 5, 1910.
Engelmann Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 726 and it contained 288 housing units.
Fayetteville Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 1,668 and it contained 722 housing units.
Freeburg Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 5,109 and it contained 2,118 housing units.
Lebanon Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 4,538 and it contained 2,005 housing units.
Lenzburg Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 1,047 and it contained 450 housing units.
Marissa Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 2,468 and it contained 1,175 housing units.
Mascoutah Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 8,217 and it contained 3,335 housing units.
Millstadt Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 6,718 and it contained 2,782 housing units.
New Athens Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 2,657 and it contained 1,129 housing units.
O'Fallon Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 26,053 and it contained 10,338 housing units.
Shiloh Valley Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 11,631 and it contained 4,284 housing units. Shiloh Valley Township was originally called Shiloh before its name was changed on an unknown date.
St. Clair Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 35,498 and it contained 15,366 housing units. St. Clair Township formed from a portion of Belleville Township on October 5, 1885.
Stites Township is located in St. Clair County, Illinois. As of the 2010 census, its population was 749 and it contained 326 housing units. Stites Township was originally named Brooklyn Township when it was reorganized from a portion of East St. Louis Township in February, 1888. Its name was changed to Stites in April, 1888.
Kansas Township is located in Woodford County, Illinois. As of the 2010 census, its population was 433 and it contained 172 housing units. Kansas Township formed from Palestine Township in September, 1859.
Dale Township is located in McLean County, Illinois. As of the 2010 census, its population was 1,233 and it contained 521 housing units.
United States 
Illinois 
St. Clair 
