| Code | Name | Region |
|---|---|---|
| USUEM | Munger | MI |
| USM8D | Munich | ND |
| USMGS | Munising | MI |
| USUNV | Munnsville | NY |
| USMF9 | Munroe Falls | OH |
| USMUQ | Munster | IN |
| USMUS | Murchison | TX |
| USMR5 | Murdock | IL |
| USUDK | Murdock | MN |
| USYMK | Murdock | NE |
| USFB3 | Murfreesboro | AR |
| USMUC | Murfreesboro | NC |
| USMFU | Murfreesboro | TN |
| USZMU | Murphy | NC |
| USURP | Murphy | OR |
| USMU8 | Murphy | TX |
| USMS5 | Murphys | CA |
| USMKZ | Mukwonago | WI |
| USEYQ | Mulberry | AR |
| USMUF | Mulberry | FL |
| USMU9 | Muldoon | TX |
| USZMW | Muldrow | OK |
| USMUH | Muleshoe | TX |
| USUGM | Mulga | AL |
| USMU7 | Mulino | OR |
| USMHN | Mullen | NE |
| USMU3 | Mullens | WV |
| USMHJ | Mullica Hill | NJ |
| USRMU | Mulliken | MI |
| USMXU | Mullins | SC |
| USVNE | Mulvane | KS |
| USTM9 | Mumford | TX |
| USMUB | Muncie | IL |
| USMIE | Muncie | IN |
| USUNE | Muncie | KS |
| USMUN | Muncy | PA |
| USMUJ | Mundelein | IL |
| USUIP | Mountain View | MO |
| USMOU | Mountain Village | AK |
| USMSJ | Mountainside | NJ |
| USMMV | Mountainville | NJ |
| USHHF | Mountainville | NY |
| USXJI | Mountlake Terrace | WA |
| USZMM | Mounts Mills | NJ |
| USTVU | Mountville | GA |
| USXJH | Mountville | PA |
| USUTV | Mountville | SC |
| USMO4 | Mouth Of Wilson | VA |
| USMC7 | Mouthcard | KY |
| USM5O | Moville | IA |