| Code | Name | Region |
|---|---|---|
| USTFS | Southfields | NY |
| USOUH | Southgate | KY |
| USSFA | Southgate | MI |
| USHH7 | Southhaven | MS |
| USSNG | Southington | CT |
| USZLE | Southlake | TX |
| USOUX | Southold | NY |
| USUTP | Southport | CT |
| USSP4 | Southport | IN |
| USP8R | Southport | ME |
| USXMK | Southport | NC |
| USUIK | Southside | AL |
| USXMR | Southwark | PA |
| USW8S | Southwest Harbor | ME |
| USSW8 | Southwest Pass | |
| US9SW | Southwest Ranches | FL |
| USSZW | Southwick | MA |
| USSWY | Spanaway | WA |
| USISG | Spangle | WA |
| USSW4 | South West City | MO |
| USNZW | South Weymouth | MA |
| USQHW | South Whitley | IN |
| USIOH | South Willamsport | PA |
| USUWH | South Windham | CT |
| USSWX | South Windham | ME |
| USXMM | South Windsor | CT |
| USXZR | South Windsor | NY |
| USOUY | South Yarmouth | MA |
| USTN6 | Southampton | MA |
| USZFJ | Southampton | NJ |
| USSSK | Southampton | NY |
| USSJL | Southampton | PA |
| USSSF | Southard | OK |
| USSVQ | Southaven | MS |
| USSZV | Southborough | MA |
| USTHD | Southbridge | MA |
| USSBU | Southbury | CT |
| USSOP | Southern Pines | NC |
| USSFX | Southfield | MA |
| USSR3 | South Rockwood | MI |
| USRXS | South Roxana | IL |
| USYLN | South Royalton | VT |
| USSPT | South Saint Paul | MN |
| USTDQ | South Salem | NY |
| USS8K | South Salt Lake | UT |
| USSYF | South San Francisco | CA |
| USSSH | South Shore | KY |
| USSSO | South Sioux City | NE |
| USS8S | South Solon | OH |
| USS2S | South Sumter | SC |