| Code | Name | Region |
|---|---|---|
| USPKA | Napaskiak | AK |
| USNPV | Naperville | IL |
| USAPF | Naples | FL |
| USN6P | Naples | IL |
| USYUD | Naples | ME |
| USNPL | Naples | NC |
| USNPK | Naples | NY |
| USNPJ | Naples | TX |
| USUMU | Mustang | OK |
| USM7R | Mustang Ridge | TX |
| USYKC | Myakka City | FL |
| USDYF | Myers Flat | CA |
| USYES | Myerstown | PA |
| USMV5 | Myersville | MD |
| USXJL | Myrtle | MS |
| USMYR | Myrtle Beach | SC |
| USYTK | Myrtle Creek | OR |
| USGY7 | Myrtle Grove | FL |
| USMYG | Myrtle Grove | LA |
| USMFG | Myrtle Point | OR |
| USMYC | Mystic | CT |
| USM7O | Myton | UT |
| USNJB | Nabb | IN |
| USYNA | Naches | WA |
| USNAC | Naco | AZ |
| USOCH | Nacogdoches | TX |
| USKQV | Nags Head | NC |
| USN5H | Nahant | MA |
| USM9U | Murphysboro | IL |
| USQRU | Murray | IA |
| USCEY | Murray | KY |
| US7MU | Murray | NE |
| USMUY | Murray | UT |
| USMRR | Murray Hill | NJ |
| USWQ2 | Murraysville | WV |
| USGGQ | Murrayville | GA |
| USRT3 | Murrells Inlet | SC |
| USMHQ | Murrieta | CA |
| USXYS | Murrysville | PA |
| USMMG | Murtaugh | ID |
| USMUT | Muscatine | IA |
| USUSH | Muscle Shoals | AL |
| USMUZ | Muscoda | WI |
| USUSG | Muskego | WI |
| USMKG | Muskegon | MI |
| US5MO | Muskegon Heights | MI |
| USMKO | Muskogee | OK |
| USUOB | Munford | AL |
| USM7F | Munford | TN |
| USUNF | Munfordville | KY |