| Code | Name | Region |
|---|---|---|
| USURL | Summerdale | AL |
| USFSF | Summerfield | FL |
| USUME | Summerfield | NC |
| USKSF | Summerfield | TX |
| USSUH | Summerhill | PA |
| USUMD | Summerland | CA |
| USSK3 | Summerland Key | FL |
| USS3U | Summers | AR |
| USSU8 | Summerset | IA |
| USUGC | Sugar Creek | OH |
| USS2G | Sugar Grove | IL |
| USSGX | Sugar Grove | PA |
| USUGH | Sugar Hill | GA |
| US9SU | Sugar Hill | NH |
| USSGR | Sugar Land | TX |
| USUGL | Sugar Loaf | NY |
| USS9N | Sugar Run | PA |
| USUGA | Sugar Valley | GA |
| USZSU | Sugarcreek | OH |
| USTKB | Sugarland | MD |
| USSIX | Suisun City | CA |
| USSIL | Suitland | MD |
| USSUG | Sulligent | AL |
| USULI | Sullivan | IL |
| USSIV | Sullivan | IN |
| US9VA | Sullivan | ME |
| USXSV | Sullivan | MO |
| USULV | Sullivan | NH |
| USUVS | Sullivan | OH |
| USIRS | Sturgis | MI |
| USS5G | Sturgis | MS |
| USZTI | Sturgis | SD |
| USSRX | Sturtevant | WI |
| USSGT | Stuttgart | AR |
| USVUR | Stuttgart | AR |
| USS9U | Suamico | WI |
| USSB9 | Sublette | KS |
| USSUZ | Sublimity | OR |
| USSQJ | Succasunna | NJ |
| USSUQ | Success | MO |
| USSDU | Sudan | TX |
| USSUR | Sudbury | MA |
| US3SM | Sudlersville | MD |
| USSUJ | Suffern | NY |
| USXLV | Suffield | CT |
| USF7D | Suffield | OH |
| USSUF | Suffolk | VA |
| USHJD | Sugar City | ID |
| USSKX | Sugar Creek | MO |
| USSG6 | Stringtown | OK |