| Code | Name | Region |
|---|---|---|
| USAWX | Athens | TX |
| USTHZ | Athens | WI |
| USAT6 | Athens | WV |
| USATC | Atherton | CA |
| USATD | Athol | ID |
| USAHO | Athol | MA |
| USAKB | Atka | AK |
| USATF | Atkins | AR |
| USA9S | Ashville | NY |
| USASO | Ashville | OH |
| USA22 | Ashville | PA |
| USAWB | Ashwaubenon | WI |
| USOAX | Asotin | WA |
| USASE | Aspen | CO |
| USA3S | Aspermont | TX |
| USUBR | Aspers | PA |
| USAI7 | Assaria | KS |
| USASJ | Assonet | MA |
| USAMP | Assumption | IL |
| USAUA | Astatula | FL |
| USA8T | Asti | CA |
| USXBF | Aston | PA |
| USAT4 | Astoria | IL |
| USAST | Astoria | OR |
| USA9T | Astoria | SD |
| USASA | Astoria/queens/new York | NY |
| USAFC | Atascadero | CA |
| USAT9 | Atascocita | TX |
| USXBH | Ashland | PA |
| USAYQ | Ashland | TN |
| US6TA | Ashland | TX |
| USALD | Ashland | VA |
| USASX | Ashland | WI |
| USXBN | Ashland City | TN |
| USHTS | Ashland-huntington Apt | WV |
| USAS4 | Ashley | IL |
| USESH | Ashley | IN |
| USAS6 | Ashley | MI |
| USASY | Ashley | ND |
| USAHY | Ashley | PA |
| USAOH | Ashmore | IL |
| USASF | Ashtabula | OH |
| USASV | Ashton | ID |
| USAYA | Ashton | IL |
| USXST | Ashton | MD |
| USHJT | Ashton | NE |
| USAS2 | Ashton | RI |
| US9AL | Ashville | AL |
| USAS5 | Ashfield | MA |
| USAF2 | Ashford | AL |