| Code | Name | Region |
|---|---|---|
| USSEE | Snellville | GA |
| USSNI | Snohomish | WA |
| USNQA | Snoqualmie | WA |
| USA3Q | Snoqualmie Pass | WA |
| USV8S | Snover | MI |
| USNSW | Snow Hill | MD |
| USXSW | Snow Hill | NC |
| USYWV | Snow Shoe | PA |
| US4SN | Snowbird | UT |
| USSFZ | Smithfield | RI |
| USFTU | Smithfield | UT |
| USSMT | Smithfield | VA |
| USZSM | Smiths | NC |
| USSDF | Smiths Creek | MI |
| USSK6 | Smiths Grove | KY |
| USJHG | Smithsburg | MD |
| UST9A | Smithton | MO |
| USTQQ | Smithton | MO |
| USITN | Smithton | PA |
| USSTY | Smithtown | NY |
| USSKH | Smithville | AR |
| USSMI | Smithville | GA |
| USXT8 | Smithville | MS |
| USYSM | Smithville | TN |
| USS2V | Smithville, Bastrop | TX |
| USQSM | Smithville, Ritchie | WV |
| USIHV | Smithville, Wayne | OH |
| USQSQ | Smock | PA |
| USKTW | Smoketown | PA |
| USSVT | Slippery Rock | PA |
| USNN6 | Sloan | NV |
| USOTB | Sloatsburg | NY |
| USUXM | Slocum | RI |
| USSK4 | Smackover | AR |
| US8PT | Small Point | ME |
| USRQA | Smarr | GA |
| USSDB | Smartt | TN |
| USYSV | Smelterville | ID |
| USTTH | Smethport | PA |
| US8YK | Smith | KY |
| US9SC | Smith Center | KS |
| USSCJ | Smith Cove | AK |
| USIXR | Smith River | CA |
| USSM5 | Smithfield | IL |
| USSDE | Smithfield | KY |
| USS9I | Smithfield | ME |
| USSMF | Smithfield | NC |
| USUYV | Smithfield | OH |
| USSF3 | Smithfield | PA |
| USXSL | Slater | CO |