| Code | Name | Region |
|---|---|---|
| USSE4 | Sedan | KS |
| USS2Y | Sedley | VA |
| USSDX | Sedona | AZ |
| USSW2 | Sedro Woolley | WA |
| USSWK | Seekonk | MA |
| USSY4 | Seeley | CA |
| USEFF | Seffner | FL |
| USSQU | Seguin | TX |
| USO8K | Seiling | OK |
| USSEC | Seiple | PA |
| USEHW | Selah | WA |
| USWLK | Selawik | AK |
| USSEL | Selby | CA |
| USYVD | Selbyville | DE |
| USEXL | Selden | NY |
| USSOV | Seldovia | AK |
| USS66 | Seligman | AZ |
| USSEG | Selinsgrove | PA |
| USYSE | Seaside | OR |
| USSH2 | Seaside Heights | NJ |
| USSEZ | Seatac | WA |
| USSEA | Seattle | WA |
| USS6E | Seaview | WA |
| US8SB | Sebago | ME |
| USYKQ | Sebago Lake | ME |
| USSZG | Sebastian | FL |
| USXNB | Sebastian | TX |
| USSYD | Sebastopol | CA |
| USXLO | Sebastopol | MS |
| USSWB | Sebewaing | MI |
| USYSB | Sebree | KY |
| USSEF | Sebring | FL |
| USSEB | Sebring | OH |
| USSC4 | Secane | PA |
| USUYK | Secaucus | NJ |
| USOZQ | Secor | IL |
| USS4E | Section | AL |
| USZSY | Security | CO |
| USSEO | Seabrook | TX |
| USXLR | Seadrift | TX |
| USSFE | Seaford | DE |
| USQSF | Seaford | NY |
| USSVI | Seagoville | TX |
| USSGK | Seagraves | TX |
| USEOV | Seagrove | NC |
| USSYB | Seal Bay | AK |
| USSLH | Seal Beach | CA |
| US9VE | Seal Cove | ME |
| USZRK | Seal Rock | OR |
| USAQE | Seale | AL |