| Code | Name | Region |
|---|---|---|
| USQSB | South Burlington | VT |
| USCQ2 | South Canaan | PA |
| USOUL | South Charleston | OH |
| USSCT | South Charleston | WV |
| USOUS | South Chicago Heights | IL |
| USODT | South Dartmouth | MA |
| USSOI | South Dayton | NY |
| US8DA | South Daytona | FL |
| USDDF | South Deerfield | MA |
| USKTY | Sonora | KY |
| US7TS | Sonora | TX |
| USQS3 | Soperton | GA |
| USSAZ | Sophia | NC |
| USS9O | Sophia | WV |
| USSQQ | Soquel | CA |
| USOET | Sorrento | CA |
| USRRN | Sorrento | FL |
| USS9R | Sorrento | LA |
| US9SO | Sorrento | ME |
| USSOT | Souderton | PA |
| 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 |