| Code | Name | Region |
|---|---|---|
| USPN8 | Plain | WI |
| USPLX | Plain City | OH |
| USPLG | Plaines | IL |
| USPDY | Pittsford | NY |
| USXPD | Pittsford | VT |
| USTGV | Pittsgrove | NJ |
| USPTO | Pittston | PA |
| USP28 | Pittstown | NJ |
| USTSW | Pittstown | NY |
| USEU7 | Pittsview | AL |
| USM6D | Pittsville | MD |
| USPVO | Pittsville | MO |
| USPMN | Pitman | NJ |
| USIMJ | Pitman | PA |
| USPBR | Pitsburg | OH |
| USQQQ | Pitts | GA |
| USPBQ | Pittsboro | IN |
| USQPO | Pittsboro | NC |
| USPBG | Pittsburg | CA |
| USP7B | Pittsburg | IL |
| USPTS | Pittsburg | KS |
| US6TS | Pittsburg | NH |
| USPI9 | Pittsburg | PA |
| USPHG | Pittsburg | TX |
| USPIT | Pittsburgh | PA |
| USTFE | Pittsfield | IL |
| USPSF | Pittsfield | MA |
| USPTF | Pittsfield | ME |
| USITT | Pittsfield | NH |
| USPZF | Pittsfield | NY |
| USPTZ | Pittsfield | PA |
| USPF3 | Pittsfield | VT |
| USPYN | Pinson | AL |
| USPI2 | Pinson | TN |
| USZ4D | Pinto | MD |
| USP9O | Pinto Island | AL |
| USPJM | Pinyon Pines | CA |
| USPI4 | Pioche | NV |
| USPYH | Pioneer | OH |
| USNE4 | Pioneer | TN |
| USPN3 | Pioneer, Amador | CA |
| USPC4 | Piper City | IL |
| USPEV | Pipersville | PA |
| USPZP | Piperton | TN |
| USPPE | Pipestone | MN |
| USPQA | Piqua | OH |
| USPIU | Piru | CA |
| USPIL | Piscataway | NJ |
| USPAG | Pisgah | AL |
| USPGF | Pisgah Forest | NC |