Saint Clair County, Illinois
County: Saint Clair
Lat/Long: 38.5500, -89.9167
St. Clair County is the oldest county in the state of Illinois. When it was established in 1790, it included all of Illinois Territory east of the Mississippi River. Gradually, the Illinois legislature made new counties out of St. Clair, including neighboring Madison, Clinton, Washington, Randolph, and Monroe counties. Belleville is the seat of government.
Illinois Counties and Incorporated Municipalities (Springfield: Illinois Secretary of State, 2012), 2; John M. Peck, A Gazetteer of Illinois in Three Parts (Jacksonville, IL: R. Goudy, 1834), 97, 116, 121, 129, 134-35, 139.