| Code | Name | Region |
|---|---|---|
| USOLO | Montello | WI |
| USMY3 | Monterey | CA |
| US3MR | Monterey | MA |
| USMZY | Monterey | TN |
| USYTX | Monterey | VA |
| USMZU | Monterey Park | CA |
| USMZW | Montesano | WA |
| USMVO | Montevallo | AL |
| USMVE | Montevideo | MN |
| USMOZ | Montezuma | GA |
| USYMZ | Montezuma | IA |
| USMZM | Montezuma | IN |
| USTZM | Montezuma | KS |
| USXQZ | Montfort | WI |
| USMGM | Montgomery | AL |
| USZMR | Monrovia | MD |
| USMSE | Monsey | NY |
| USMZS | Monson | MA |
| US6MS | Monson | ME |
| USM5A | Mont Alto | PA |
| USMTG | Mont Belvieu | TX |
| USTV7 | Mont Vernon | NH |
| USSIY | Montague | CA |
| USM2G | Montague | MA |
| USTGQ | Montague | MI |
| US7UE | Montague | NJ |
| USJTA | Montana City | MT |
| USOQT | Montara | CA |
| USMTP | Montauk | NY |
| USMZT | Montclair | CA |
| USMLR | Montclair | NJ |
| USMXZ | Monte Alto | TX |
| USC4F | Monte Rio | CA |
| USVMZ | Monte Vista | CO |
| US2MO | Monteagle | TN |
| USQMX | Monroe | NJ |
| USVMO | Monroe | NY |
| USNRO | Monroe | OH |
| USOVN | Monroe | OR |
| USXZ9 | Monroe | TN |
| USNRX | Monroe | VA |
| USMOW | Monroe | WA |
| USMWI | Monroe | WI |
| USVOB | Monroe Bridge | MA |
| USKRC | Monroe City | MO |
| USMPQ | Monroe Park | NC |
| USONR | Monroe Township | NJ |
| USOOE | Monroe, Tippecanoe | IN |
| USMVC | Monroeville | AL |
| US9MO | Monroeville | IN |