| Code | Name | Region |
|---|---|---|
| USYMQ | Moweaqua | IL |
| USXXE | Moxee City | WA |
| USIPG | Moyie Springs | ID |
| USM4Y | Moyock | NC |
| USMST | Muenster | TX |
| USH98 | Muhlenberg | PA |
| USMKI | Mukilteo | WA |
| USTGM | Mountain Green | UT |
| USVMV | Mountain Grove | MO |
| USWMH | Mountain Home | AR |
| USMUO | Mountain Home | ID |
| USMHU | Mountain Home | NC |
| USMUM | Mountain Home | TN |
| USHPQ | Mountain House | CA |
| USUII | Mountain Iron | MN |
| USML5 | Mountain Lake | MN |
| USUTK | Mountain Lake Park | MD |
| USULS | Mountain Lakes | NJ |
| USMTS | Mountain Pass | CA |
| USM6O | Mountain Ranch | CA |
| USMU5 | Mountain Rest | SC |
| USMUV | Mountain Top | PA |
| USMUL | Mountain View | AL |
| USVAJ | Mountain View | AR |
| USNUQ | Mountain View | CA |
| USMUK | Mountain View | GA |
| US5MV | Mountain View | HI |
| USMXH | Mount Vernon | IN |
| USMXV | Mount Vernon | KY |
| USUEO | Mount Vernon | ME |
| USOUV | Mount Vernon | MO |
| USYMV | Mount Vernon | NY |
| USMVH | Mount Vernon | NY |
| USM2V | Mount Vernon | OH |
| USMWT | Mount Vernon | OH |
| USMVX | Mount Vernon | TX |
| USMV3 | Mount Vernon | TX |
| USMVW | Mount Vernon | WA |
| USUMX | Mount Washington | KY |
| USMWS | Mount Wilson | CA |
| USMWF | Mount Wolf | PA |
| USUTZ | Mount Zion | IL |
| USMU4 | Mountain | WI |
| USM77 | Mountain Brook | AL |
| USCZJ | Mountain Center | CA |
| USTKM | Mountain City | GA |
| USMFM | Mountain City | TN |
| USMUP | Mount Prospect | IL |
| USMPK | Mount Pulaski | IL |
| US9MY | Mount Royal | NJ |