| Code | Name | Region |
|---|---|---|
| USPUL | Poulsbo | WA |
| USYPU | Poultney | VT |
| USPN4 | Pound | VA |
| USPWJ | Pound | WI |
| USPG8 | Pound Ridge | NY |
| USPDM | Pounding Mill | VA |
| USQPW | Poway | CA |
| USPDS | Powder Springs | GA |
| USTXX | Powderly | TX |
| USPO5 | Powell | OH |
| USTNO | Powell | TN |
| USPRQ | Powell | WY |
| USPZO | Posen | IL |
| USPS2 | Posen | MI |
| USPYZ | Poseyville | IN |
| USPUK | Poskin | WI |
| USPZS | Post | TX |
| USPFI | Post Falls | ID |
| USPM7 | Post Mills | VT |
| USVVI | Postville | IA |
| USRKR | Poteau | OK |
| USPT8 | Poteet | TX |
| US5PT | Potlatch | ID |
| USPMK | Potomac | MD |
| USVPM | Potomac Falls | VA |
| USPSI | Potosi | MO |
| UST8P | Potrero | CA |
| USPPT | Potsdam | NY |
| USPT6 | Potter | WI |
| USPV2 | Potter Valley | CA |
| USPOG | Pottersburg | OH |
| USTTJ | Potterstown | NJ |
| USLDP | Portland | AR |
| USPTQ | Portland | CT |
| USPJD | Portland | IN |
| USPOL | Portland | MD |
| USPWM | Portland | ME |
| USPWQ | Portland | MI |
| USO2H | Portland | OH |
| USPDX | Portland | OR |
| USXPO | Portland | PA |
| USPQD | Portland | TN |
| USDTP | Portland | TX |
| USPM6 | Portland Mills | PA |
| USPXB | Portola | CA |
| USXPT | Portola Valley | CA |
| USOUQ | Portsmouth | IA |
| USPSM | Portsmouth | NH |
| USPMH | Portsmouth | OH |
| USPOM | Portsmouth | RI |