| | 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 |
| | DeKalb County | IL | 17037 | Elgin, IL 20994 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Outlying | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=DeKalbCounty+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 |
| | Grundy County | IL | 17063 | Chicago-Naperville-Schaumburg,
IL 16984 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Outlying | metro county (urban) | nonspecialized | https://maps.google.com/?q=GrundyCounty+IL |
| | Jasper County | IN | 18073 | Lake County-Porter
County-Jasper County, IN 29414 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Outlying | metro county (urban) | nonspecialized | https://maps.google.com/?q=JasperCounty+Indiana |
| | Kane County | IL | 17089 | Elgin, IL 20994 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=KaneCounty+IL |
| | Kendall County | IL | 17093 | Elgin, IL 20994 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=KendallCounty+IL |
| | Lake County | IL | 17097 | Lake County, IL 29404 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=LakeCounty+IL |
| | Lake County | IN | 18089 | Lake County-Porter
County-Jasper County, IN 29414 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=LakeCounty+Indiana |
| | McHenry County | IL | 17111 | 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=McHenryCounty+IL |