St. Clair County on the map of Illinois 2024. Cities, roads, borders and directions in St. Clair County of Illinois.

St. Clair County is found in the Metro East region of Illinois. This famous county was named after Arthur St. Clair (1737-1818), major general in the American Revolutionary War. The population of St. Clair County exceeds 255 thousand people. The county, organized in 1790, covers an area of 657 square miles. The county seat of St. Clair County is Belleville. This map shows the borders of St. Clair County as well as neighboring counties, including major highways and natural objecsts as of 2024. Zoom in or out of the map using the plus/minus panel. Move the center of this map by dragging it. Also check out the satellite map of St. Clair County.