| | Christian County | IL | 17021 | | Taylorville, IL 45380 | Springfield-Jacksonville-Lincoln,
IL 522 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=ChristianCounty+IL |
| | Clark County | IL | 17023 | | | | | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=ClarkCounty+IL |
| | Clay County | IL | 17025 | | | | | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=ClayCounty+IL |
| | Clinton County | IL | 17027 | | St. Louis, MO-IL 41180 | St. Louis-St.
Charles-Farmington, MO-IL 476 | Outlying | metro county (urban) | nonspecialized | https://maps.google.com/?q=ClintonCounty+IL |
| | Coles County | IL | 17029 | | Charleston-Mattoon, IL 16660 | | Central | nonmetro county (rural) | federal/state
government-dependent | https://maps.google.com/?q=ColesCounty+IL |
| | Crawford County | IL | 17033 | | | | | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=CrawfordCounty+IL |
| | Cumberland County | IL | 17035 | | Effingham, IL 20820 | | Outlying | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=CumberlandCounty+IL |
| | De Witt County | IL | 17039 | | | | | metro county (urban) | nonspecialized | https://maps.google.com/?q=DeWittCounty+IL |
| | Douglas County | IL | 17041 | | | | | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=DouglasCounty+IL |
| | Edgar County | IL | 17045 | | | | | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=EdgarCounty+IL |