Adams County, Illinois

Formed in 1825 from Pike County

Bureau County, Illinois

Bureau County was formed in 1837 from Putnam County.

Clark County, Illinois

Clark County was formed in 1819 from Crawford County.

Coles County, Illinois

Coles County was formed in 1830 from Clark and Edgar Counties.

Cook County, Illinois

Cook County was formed in 1831 from Putnam County.

Crawford County, Illinois

Crawford County was formed in 1816 from Edwards County.