| | Adams County | IL | 17001 | | Quincy, IL-MO 39500 | Quincy-Hannibal, IL-MO 448 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=AdamsCounty+IL |
| | Brown County | IL | 17009 | | | | | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=BrownCounty+IL |
| | Bureau County | IL | 17011 | | Ottawa, IL 36837 | Chicago-Naperville,
IL-IN-WI 176 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=BureauCounty+Illinois |
| | Carroll County | IL | 17015 | | | | | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=CarrollCounty+IL |
| | Christian County | IL | 17021 | | Taylorville, IL 45380 | Springfield-Jacksonville-Lincoln,
IL 522 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=ChristianCounty+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 |
| | Cook County | IL | 17031 | Chicago-Naperville-Schaumburg,
IL 16984 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=CookCounty+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 |
| | DuPage County | IL | 17043 | Chicago-Naperville-Schaumburg,
IL 16984 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=DuPageCounty+IL |