| Code | Name | Region |
|---|---|---|
| USCZL | Corte Madera | CA |
| USCEZ | Cortez | CO |
| USC5Z | Cortez | FL |
| USTND | Cortland | IL |
| USCJ8 | Cortland | IN |
| USCTX | Cortland | NY |
| USZB9 | Cortland | OH |
| USOXQ | Corunna | IN |
| USC22 | Corunna | MI |
| USYCV | Corvallis | MT |
| USCVL | Corvallis | OR |
| USOWZ | Corwith | IA |
| USCY8 | Cory | IN |
| USCZB | Corydon | IN |
| USCD2 | Corydon, Wayne | IA |
| USOCB | Cos Cob | CT |
| US7CB | Cosby | MO |
| USCB3 | Cosby | TN |
| USCSC | Coshocton | OH |
| US9IS | Cornish | ME |
| US8CO | Cornish | NH |
| USC35 | Cornville | AZ |
| USW7N | Cornwall | CT |
| USOQW | Cornwall | VT |
| USNWL | Cornwall, Town Of | NY |
| USCZD | Cornwells Heights | PA |
| USZZC | Corolla | NC |
| USCZE | Corona | CA |
| USQYC | Corona | NY |
| USCM2 | Corona Del Mar | CA |
| USCD4 | Coronado | CA |
| USCRP | Corpus Christi | TX |
| USCE3 | Corrales | NM |
| USTO3 | Corralitos | CA |
| USCV4 | Correctionville | IA |
| USIGZ | Corrigan | TX |
| USCYP | Corry | PA |
| US4CO | Corsica | SD |
| USCRS | Corsicana | TX |
| USCYV | Cordova | WV |
| USRFU | Corfu | NY |
| USVJA | Corinna | ME |
| USJCE | Corinne | UT |
| US8CH | Corinth | ME |
| USCRX | Corinth | MS |
| USOIH | Corinth | NY |
| USXEM | Corinth | TN |
| USTX9 | Corinth | TX |
| US7OR | Corinth | VT |
| USCZA | Cornelia | GA |