| Code | Name | Region |
|---|---|---|
| USIFO | Spanish Fort | AL |
| USZUS | Spanish Springs | NV |
| USSPM | Sparks | GA |
| USSRM | Sparks | MD |
| USKP3 | Sparks | NE |
| USSPK | Sparks | NV |
| USFKG | Sparks Glencoe | MD |
| USSVW | Sparrevohn | AK |
| USPWU | Sparrow Bush | NY |
| USPPO | Sparrows Point | MD |
| USAA5 | Sparta | GA |
| USSAR | Sparta | IL |
| USSQH | Sparta | MI |
| USZSR | Sparta | NC |
| USSZA | Sparta | NJ |
| USSPX | Sparta | TN |
| USCMY | Sparta | WI |
| USSPA | Spartanburg | SC |
| USSPB | Spartansburg | PA |
| USSFJ | Southfield | MI |
| 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 |