| Code | Name | Region |
|---|---|---|
| USMVG | Middle Village | NY |
| USMID | Middleboro | MA |
| USM4B | Middlebourne | WV |
| USXXX | Mexico | ME |
| USMXI | Mexico | MO |
| USZGJ | Mexico Beach | FL |
| USWMK | Meyers Chuck | AK |
| USMYD | Meyersdale | PA |
| US4MI | Miami | AZ |
| USMIA | Miami | FL |
| USMIO | Miami | OK |
| USIMV | Miami | TX |
| USIYH | Miami Beach | FL |
| USJDM | Miami Downtown Heliport Airport | FL |
| USZMG | Miami Gardens | FL |
| USMMK | Miami Lakes | FL |
| USKKV | Miami River | FL |
| USM4I | Miami Shores | FL |
| USMIZ | Miami Springs | FL |
| USIAM | Miamisburg | OH |
| USIMW | Miamitown | OH |
| USMAM | Miamiville | OH |
| USICM | Mica | WA |
| USME9 | Mesopotamia | OH |
| USMQS | Mesquite | NM |
| USMFH | Mesquite | NV |
| USMSQ | Mesquite | TX |
| USMZB | Meta | MO |
| USMTE | Metairie | LA |
| USMTF | Metaline Falls | WA |
| USEOA | Metamora | IL |
| USMM3 | Metamora | MI |
| USEMF | Metamora | OH |
| USMZN | Methuen | MA |
| USMTM | Metlakatla | AK |
| US2MT | Metolius | OR |
| USMET | Metropolis | IL |
| USMT2 | Mettawa | IL |
| USTTR | Metter | GA |
| USM8T | Mettler | CA |
| USMEU | Metuchen | NJ |
| USMTY | Metzger | OR |
| USMAX | Mexia | TX |
| USVMR | Merrill | OR |
| USRRL | Merrill | WI |
| USMEL | Merrillville | IN |
| USMM2 | Merrimac | MA |
| USRM8 | Merrimac | WI |
| USMRM | Merrimack | NH |
| USMBF | Merritt Island | FL |