| Code | Name | Region |
|---|---|---|
| USPF2 | Plainfield | TN |
| USPF4 | Plainfield | VT |
| USLNF | Plainfield | WI |
| USXPF | Plainfield Center | NY |
| USPLS | Plains | GA |
| USP4L | Plains | KS |
| USLPY | Plains | PA |
| USPLJ | Plains | TX |
| USXKM | Plainsboro | NJ |
| USPVN | Plainview | MN |
| USPFW | Plainview | NE |
| USPVX | Plainview | NY |
| 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 |
| USPVQ | Pittsville | PA |
| USITV | Pittsville | WI |
| USPXY | Pixley | CA |
| USP9C | Placedo | TX |
| USPCC | Placentia | CA |
| USPVF | Placerville | CA |
| USEUU | Placida | FL |
| US9LA | Placitas | NM |
| USPN8 | Plain | WI |
| USPLX | Plain City | OH |
| USPLG | Plaines | IL |
| 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 |