| Code | Name | Region |
|---|---|---|
| USCUN | Conover | NC |
| USC3W | Conowingo | MD |
| USIWR | Conrad | IA |
| USCD6 | Conrad | MT |
| USCXO | Conroe | TX |
| USOQO | Conroy | IA |
| USCSH | Conshohocken | PA |
| USTNJ | Constantine | MI |
| USNIU | Continental | OH |
| USJJD | Concord | MI |
| USXEA | Concord | NC |
| USCON | Concord | NH |
| USODZ | Concord | TX |
| USFGF | Concord | VA |
| US7CD | Concord | VT |
| USLCX | Concord, Lake | OH |
| USCNK | Concordia | KS |
| USC5O | Concordia | MO |
| USONC | Concordville | PA |
| USNQC | Concrete | WA |
| USQSE | Conestee | SC |
| USC5A | Conestoga | PA |
| USOIP | Conesville | OH |
| USWG7 | Conewango Valley | NY |
| USC7N | Confluence | PA |
| USNGS | Congers | NY |
| USZB7 | Congo | WV |
| USNZF | Congress | AZ |
| USOIF | Conifer | CO |
| US6CR | Comer | GA |
| USOMF | Comfort | TX |
| USCMF | Commack | NY |
| USZEC | Commerce | GA |
| USOMR | Commerce | OK |
| USOMC | Commerce | TX |
| USCMT | Commerce City | CO |
| USOMM | Commerce Township | MI |
| USCRC | Commerce/los Angeles | CA |
| USQOM | Como | MS |
| USCPM | Compton | CA |
| USKVO | Compton | IL |
| USCVC | Comstock | MI |
| USYCM | Comstock Park | MI |
| USCZY | Comyn | TX |
| USNZN | Concan | TX |
| USKZO | Concho | AZ |
| USCCR | Concord | CA |
| USJQQ | Concord | GA |
| USCCF | Concord | MA |
| USCZX | Columbus | NC |