| Code | Name | Region |
|---|---|---|
| USADX | Addison | OH |
| USQDS | Addison | PA |
| USDDX | Addison | TX |
| USUAS | Addyston | OH |
| USADE | Adel | GA |
| USZAE | Adel | IA |
| USADU | Adelanto | CA |
| USAJD | Adell | WI |
| USKUS | Acushnet | MA |
| USAWR | Acworth | GA |
| US6WT | Acworth | NH |
| USADZ | Ada | MI |
| USDD2 | Ada | MN |
| USAJJ | Ada | OH |
| USADT | Ada | OK |
| USA59 | Adair | IA |
| US2AR | Adair | OK |
| USADV | Adairsville | GA |
| USAD3 | Adairville | KY |
| USAXK | Adak | AK |
| USADK | Adak Island/adak Apt | AK |
| USUAN | Adams | MA |
| USUAT | Adams | OR |
| USAKM | Adams | TN |
| USAZM | Adams | WI |
| USADH | Adams Center | NY |
| USYP2 | Adams City | CO |
| USTPG | Abita Springs | LA |
| USQYA | Abrams | WI |
| USACX | Absecon | NJ |
| USAA4 | Acampo | CA |
| USAJT | Accident | MD |
| USJOK | Accokeek | MD |
| USAQC | Accomac | VA |
| USA8C | Accord | MA |
| USAC9 | Accord | NY |
| USACR | Ackerman | GA |
| USUAG | Ackerman | MS |
| USAKY | Ackley | IA |
| USDMF | Acme | MI |
| USQZA | Acme | WA |
| USQCA | Acra | NY |
| USAXJ | Acton | CA |
| UST5C | Acton | IN |
| USUAH | Acton | MA |
| US8ON | Acton | ME |
| USTZO | Acton | TX |
| USAPD | Aberdeen | ID |
| USABK | Aberdeen | KY |
| USAPG | Aberdeen | MD |