| Code | Name | Region |
|---|---|---|
| USA9B | South Abington | PA |
| USS6A | South Albany | NY |
| USZZM | South Amboy | NJ |
| USJSB | South Attleboro | MA |
| USS9B | South Baltimore | MD |
| USSB5 | South Barre | MA |
| USUHB | South Barrington | IL |
| USSOF | South Bay | FL |
| USBS6 | South Beach | OR |
| USSME | Somerset | KY |
| USS73 | Somerset | LA |
| USSS3 | Somerset | MA |
| USSOJ | Somerset | NJ |
| USSZR | Somerset | PA |
| USSOZ | Somerset | TX |
| USOMP | Somerset | WI |
| USOFV | Somersville | CT |
| USSSX | Somersworth | NH |
| USSN7 | Somerton | AZ |
| USILX | Somerville | AL |
| USUZB | Somerville | MA |
| USSOM | Somerville | NJ |
| USOMV | Somerville | OH |
| USQSV | Somerville | TN |
| USSSJ | Somis | CA |
| USSM7 | Somonauk | IL |
| USQNI | Sonoita | AZ |
| USSOY | Sonoma | CA |
| USSOR | Sonora | CA |
| USSZB | Solana Beach | CA |
| USJDG | Soldiers Grove | WI |
| USSXQ | Soldotna | AK |
| USZOL | Soledad | CA |
| USSOL | Solomon | AK |
| USSZO | Solomon | KS |
| USOMU | Solomons | MD |
| USSI5 | Solon | IA |
| USSO6 | Solon | ME |
| USSOO | Solon | OH |
| USOLG | Solvang | CA |
| USOVA | Solvay | NY |
| USL4W | Solway | MN |
| USSMV | Somerdale | NJ |
| USTSF | Somers | CT |
| USOFP | Somers | MT |
| USOJS | Somers | NY |
| USS5P | Somers Point | NJ |
| US6ST | Somerset | CA |
| USOMT | Somerset | CO |
| USSFL | Snowflake | AZ |