| Code | Name | Region |
|---|---|---|
| USS5U | Sumner | MS |
| USUMN | Sumner | TX |
| USXMH | Sumner | WA |
| USS5N | Sumneytown | PA |
| USUAL | Sumrall, Lamar | MS |
| USSSC | Sumter | SC |
| USUMV | Sumterville | FL |
| USSCI | Sun City | AZ |
| USXZI | Sun City | CA |
| USSJY | Sun City | FL |
| USUNY | Sun City | KS |
| USSPE | Sun Prairie | WI |
| USSUO | Sun River | OR |
| USSVY | Sun Valley | CA |
| US5SV | Sun Valley | ID |
| USJUV | Sun Valley | NV |
| USKEP | Sunapee | NH |
| US7SM | Sunburst | MT |
| USSRZ | Sunbury | OH |
| USSWV | Summersville | WV |
| USUMR | Summerton | SC |
| USZSE | Summerville | GA |
| USURV | Summerville | PA |
| USUZC | Summerville | SC |
| USUMM | Summit | AK |
| USSMZ | Summit | AL |
| USXMV | Summit | IL |
| USITG | Summit | IL |
| US2MM | Summit | MS |
| USUYX | Summit | NJ |
| USSZS | Summit | PA |
| USAAO | Summit | SC |
| USSWP | Summit Point | WV |
| USSM9 | Summit Station | PA |
| USVVL | Summitville | IN |
| USSVO | Summitville | OH |
| USSXG | Sumner | GA |
| US5SU | Sumner | IA |
| USS8U | Sumner | ME |
| USUVT | Sullivan City | TX |
| USULX | Sully | IA |
| USSLP | Sulphur | LA |
| USLPU | Sulphur | OK |
| USUUS | Sulphur Springs | AR |
| USSLR | Sulphur Springs | TX |
| USULN | Sultan | WA |
| USULT | Sultana | CA |
| USACF | Sumas | WA |
| USASZ | Sumiton | AL |
| USSU4 | Summer Shade | KY |