| Code | Name | Region |
|---|---|---|
| USQTW | Stewartsville | NJ |
| USSV7 | Stewartville | MN |
| USSKT | Stickney | IL |
| USVVR | Stigler | OK |
| USLLM | Stillmore | GA |
| USTIS | Stillwater | MN |
| USVSW | Stillwater | NJ |
| USIWZ | Stillwater | NY |
| USIAK | Stillwater | OH |
| USS9G | Sterling | CT |
| USSGI | Sterling | IL |
| USS8R | Sterling | KS |
| USXLS | Sterling | MA |
| USSKA | Sterling | MI |
| USRZF | Sterling | ND |
| USHZ3 | Sterling | OH |
| USSEK | Sterling | PA |
| USSGV | Sterling | VA |
| USYTE | Sterling City | TX |
| USSEH | Sterling Heights | MI |
| USSQI | Sterling-rockfalls Apt | IL |
| USSEX | Sterlington | LA |
| UST67 | Sterrett | AL |
| US8TE | Stetson | ME |
| US9SE | Steuben | ME |
| USUYJ | Steubenville | OH |
| USSS7 | Stevens | PA |
| USSTE | Stevens Point | WI |
| USSVS | Stevens Village | AK |
| USSBS | Steamboat Springs | CO |
| USWBB | Stebbins | AK |
| USYDM | Stedman | NC |
| USS5M | Steedman | MO |
| USSXI | Steele | AL |
| USQTL | Steele | MO |
| USNDZ | Steele | ND |
| USVTS | Steeleville | IL |
| USQQX | Steelton | PA |
| USQTV | Steelville | MO |
| USSGQ | Steger | IL |
| USSIC | Steilacoom | WA |
| USTST | Stennis Space Center | MS |
| USZSP | Stephen | MN |
| US4ST | Stephens | VA |
| USEPS | Stephenson | MI |
| USTEP | Stephentown | NY |
| USSEP | Stephenville | TX |
| USSIG | Sterling | AK |
| USSTK | Sterling | CO |
| US5ST | Star City | AR |