| Code | Name | Region |
|---|---|---|
| USOOR | Moorestown | PA |
| USMYZ | Mooresville | IN |
| US2MV | Mooresville | MO |
| USXJK | Mooresville | NC |
| USM3O | Mooresville | TN |
| USXIH | Moorhead | MN |
| USMPF | Moorlands | WA |
| USMBH | Montrose | CA |
| USMTJ | Montrose | CO |
| US4MO | Montrose | IA |
| USME3 | Montrose | MN |
| USQMR | Montrose | PA |
| USKMX | Montross | VA |
| USQMV | Montvale | NJ |
| USM8V | Montvale | VA |
| USMBM | Montville | CT |
| USMDB | Montville | NJ |
| USZPQ | Montz | LA |
| USMEB | Monument | CO |
| USJUM | Monument | KS |
| USGMV | Monument Valley Gldngs | UT |
| USMU2 | Moodus | CT |
| USMD7 | Moody | AL |
| USOOY | Moody | TX |
| USMO3 | Mooers | NY |
| USM2F | Mooers Forks | NY |
| USNIP | Moon | PA |
| USOIO | Monticello | IN |
| USMOC | Monticello | KY |
| USM8L | Monticello | ME |
| USOTC | Monticello | MN |
| USMCZ | Monticello | MS |
| USMSV | Monticello | NY |
| USMXC | Monticello | UT |
| USIEO | Monticello | WI |
| USZGI | Montmorenci | IN |
| USURF | Montour Falls | NY |
| USMBC | Montoursville | PA |
| USIUW | Montpelier | ID |
| USOPQ | Montpelier | IN |
| USMMP | Montpelier | OH |
| USXIX | Montpelier | VA |
| USMPI | Montpelier | VT |
| USMT8 | Montreal | MO |
| USM2T | Montreal | OH |
| USOZ9 | Montrose | AL |
| USXIL | Montgomery | IL |
| USOGM | Montgomery | IN |
| US3MG | Montgomery | LA |
| USMGH | Montgomery | MN |