Find schools and get information on the program that’s right for you.
Powered by Campus Explorer
St. Clair County is the oldest county in the state of Illinois. According to the 2010 census, it had a
population of 270,056, making
it the eighth most populous county in Illinois. St Clair County was
created on April 27, 1790. The county
seat is Belleville. The county is named
for Arthur St. Clair (1737-1818), major general in the American
Revolutionary War and first Governor of the Northwest Territory.
St. Clair County is part of the American Bottom or Metro-East area of the St. Louis, MO-IL Metropolitan Statistical Area.
The county is named for General Arthur St. Clair, Commander in Chief of the United States Army after the American Revolution and Governor of United States Territory northwest of the Ohio River.
County QuickFacts: CensusBureau Quick Facts
St Clair County was created on April 27, 1790 (Territorial Records of the Northwest Territory, St. Clair Papers, Vol.
2, p. 165) and was formed from the Northwest Territory. Present area, or parts of it, formerly included in: St. Clair
County was the first county established in Illinois, at the time a part of the Northwest Territory.
The County was named for Arthur St. Clair, a soldier of the French and Indian wars, a Major General during the Revolution, Commander-in-Chief of the Army after the Revolution, and Governor of the Territory of the United States northwest of the Ohio River. The County Seat is Belleville . Prior County Seats was Cahokia* (1790-1814), Kaskaskia* (1790-1795), Prairie du Rocher* (1790-1795) and Belleville (1814-Present).
As reported by the Census Bureau, the county has a total area of 674 square miles (1,746 km2), of which, 664 square miles (1,719 km2) of it is land and 10 square miles (26 km2) of it (1.51%) is water.
Saint Clair county is located in south Illinois. The central portion
of St. Clair county, sitting atop the Mississippi River bluff. The
eastern and southern portion of the county is scattered with older small
communities between large swathes of corn and soybean fields. Frank
Holten State Recreation Area and part of Kaskaskia River State Fish &
Wildlife Area are located in this county.
Bordering counties are as follows: