| Code | Name | Region |
|---|---|---|
| USAEK | Aberdeen | MS |
| USUAE | Aberdeen | NC |
| USAB3 | Aberdeen | NJ |
| USAHD | Aberdeen | OH |
| USXBA | Aberdeen | SC |
| USABR | Aberdeen | SD |
| USGHR | Aberdeen | WA |
| USAN7 | Aberdin | NC |
| USUAF | Abernathy | TX |
| USABZ | Abilene | KS |
| USABI | Abilene | TX |
| USABG | Abingdon | IL |
| USNGD | Abingdon | MD |
| USVJI | Abingdon | VA |
| USUUM | Abington | MA |
| USAP3 | Abington | PA |
| USAQ2 | Abiquiu | NM |
| US | ||
| USOQU | Aaron | GA |
| USAA7 | Aaronsburg | PA |
| USABB | Abbeville | AL |
| USUAB | Abbeville | LA |
| USAV4 | Abbeville | MS |
| USABF | Abbeville | SC |
| USA8B | Abbot | ME |
| USABD | Abbotsford | WI |
| US9AB | Abbott | TX |
| USABJ | Abbott Park | IL |
| USAQW | Abbottstown | PA |
| USA4B | Abbyville | KS |
| USAC8 | Abercrombie | ND |