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St. Clair County, Illinois facts for kids

Kids Encyclopedia Facts
St. Clair County, Illinois
Map of Illinois highlighting St. Clair County
Location in the state of Illinois
Map of the USA highlighting Illinois
Illinois's location in the U.S.
Founded 1790
Seat Belleville
Largest City Belleville
 - Total
 - Land
 - Water

674 sq mi (1,746 km²)
658 sq mi (1,704 km²)
16 sq mi (41 km²), 2.4%
 - (2010)
 - Density

411/sq mi (159/km²)
Time zone Central: UTC-6/-5
Named for: Arthur St. Clair
County flag Flag of St. Clair County, Illinois

St. Clair County is the oldest county in the U.S. state of Illinois. According to the 2010 census, it had a population of 270,056, making it the eighth-most populous county in Illinois and the most populous in the southern part of the state. Its county seat is Belleville. The county was founded in 1790, before the establishment of Illinois as a state.

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St. Clair County, Illinois Facts for Kids. Kiddle Encyclopedia.