- Carbon Cliff
- Carlinville
- Carlock
- Carmi
- Carol Stream
- Carpentersville
- Carrier Mills
- Carterville
- Casey
- Caseyville
- Catlin
- Cave-in-Rock
- Chadwick
- Cuba Island
- Champaign
- Chandlerville
- Channahon
- Channel Lake
- Chebanse
- Chenoa
- Cherry
- Chicago
- Chicago Heights
- Chicago Ridge
- Cherry Wood Trailer Park
- Clarksdale
- Castle Fin
- Choctaw
- Clarksville
- Cleone