| Code | Name | Region |
|---|---|---|
| USCW9 | Crestwood | MO |
| USERX | Creswell | OR |
| USCQQ | Crete | IL |
| USEE5 | Crete | ND |
| USCTF | Crete | NE |
| USCXD | Creve Coeur | IL |
| USC4Q | Creve Coeur | MO |
| USVGW | Crewe | VA |
| USC74 | Crimora | VA |
| USUCZ | Cripple Creek | CO |
| USQAP | Creekside | PA |
| USIGQ | Creighton | NE |
| USCQK | Creighton | PA |
| USRHA | Crenshaw | MS |
| USEOZ | Creola | AL |
| USECJ | Crescent | GA |
| USCQN | Crescent | IA |
| USCEC | Crescent City | CA |
| USTCJ | Crescent City | FL |
| US3CL | Crescent Lake | OR |
| USWJC | Crescent Township | PA |
| USCFK | Cresco | IA |
| USCTG | Cresco | PA |
| USCYJ | Cresskill | NJ |
| USCR8 | Cresson | PA |
| USZJQ | Cresson | TX |
| USCJA | Cressona | PA |
| USCH5 | Crest Hill | IL |
| USCSE | Crested Butte | CO |
| USGKM | Crestline | CA |
| USUFD | Crandon Lakes | NJ |
| USZCR | Crane | IN |
| USZVQ | Crane | MO |
| USCCG | Crane | TX |
| USCKR | Crane Island | WA |
| USC8L | Crane Lake | MN |
| USCQG | Cranford | NJ |
| USCQH | Cranston | RI |
| US4CR | Craryville | NY |
| USW7D | Crawford | CO |
| USCW8 | Crawford | NE |
| USC4W | Crawford | TX |
| USCF6 | Crawfordsville | AR |
| USCFB | Crawfordsville | IN |
| USRFV | Crawfordville | FL |
| USFDI | Crawfordville | GA |
| USEFP | Creal Springs | IL |
| USCR3 | Cream Ridge | NJ |
| USZCE | Creedmoor | NC |
| USEMV | Creedmoor | TX |