| Code | Name | Region |
|---|---|---|
| USCVR | Culver City | CA |
| US4CM | Cumberland | IL |
| USUMC | Cumberland | IN |
| USHXD | Cumberland | KY |
| USCBE | Cumberland | MD |
| USCUE | Cumberland | RI |
| US5CV | Cumberland | VA |
| USZCU | Cumberland | WI |
| USUDT | Cumberland Center | ME |
| USUDC | Cumberland City | TN |
| USCZ4 | Crystal Falls | MI |
| US9CH | Crystal Hill | VA |
| USCTD | Crystal Lake | IL |
| USCYE | Crystal Lake | PA |
| US2CL | Crystal Lawns | IL |
| USYAU | Crystal Mountain | WA |
| USCJF | Crystal River | FL |
| USCYH | Crystal Springs | MS |
| USJCB | Cuba | IL |
| USOCU | Cuba | MO |
| USCUA | Cuba | NM |
| USNYB | Cuba | NY |
| USCY4 | Cuba City | WI |
| USCUW | Cube Cove | AK |
| USCUY | Cudahy | CA |
| USCUD | Cudahy | WI |
| USYCB | Cuddy | PA |
| US9CY | Cudjoe Key | FL |
| USCR4 | Cuero | TX |
| US4CU | Culbertson | MT |
| USCYO | Croton | OH |
| USC9F | Croton Falls | NY |
| USTHU | Croton-on-hudson | NY |
| USOZC | Crow Agency | MT |
| US5CM | Crowell | TX |
| USCWL | Crowley | LA |
| USOZY | Crowley | TX |
| USYOX | Crown Point | IN |
| USNRC | Crows Landing | CA |
| USV7X | Croxton | NJ |
| USCRF | Croydon | PA |
| USCZR | Crozet | VA |
| USULC | Crum Lynne | PA |
| USUMK | Crump | TN |
| USC3R | Crystal | MI |
| USYSA | Crystal | MN |
| USN8V | Crystal Bay | NV |
| US5KB | Crystal Beach | FL |
| USCCM | Crystal City | MO |
| USCYY | Crystal City | TX |