| Port Code | Port Name | Country |
| USMSJ | Mountainside | United States |
| USMSK | Mascoutah | United States |
| USMSL | Muscle Shoals-Florence Apt | United States |
| USMSL | Florence-Muscle Shoals Apt | United States |
| USMSM | Madison | United States |
| USMSN | Madison | United States |
| USMSO | Missoula | United States |
| USMSP | Minneapolis/St Paul Apt | United States |
| USMSQ | Mesquite | United States |
| USMSR | Marion | United States |
| USMSS | Massena | United States |
| USMSU | Masury | United States |
| USMSV | Monticello | United States |
| USMSW | Morris | United States |
| USMSX | Mesilla Park | United States |
| USMSY | New Orleans | United States |
| USMSZ | Moose Pass | United States |
| USMTA | Manteca | United States |
| USMTB | Montebello | United States |
| USMTC | Mt Clemens | United States |
| USMTD | Mattydale | United States |
| USMTE | Metairie | United States |
| USMTF | Metaline Falls | United States |
| USMTG | Mont Belvieu | United States |
| USMTH | Marathon | United States |
| USMTI | Morton | United States |
| USMTJ | Montrose | United States |
| USMTK | Mount Carmel | United States |
| USMTL | Millington | United States |
| USMTM | Metlakatla | United States |
| USMTN | Martin Mariet/Baltimore | United States |
| USMTO | Mattoon | United States |
| USMTP | Montauk | United States |
| USMTQ | Mattapoisett | United States |
| USMTR | Manteno | United States |
| USMTS | Mountain Pass | United States |
| USMTT | Mt Pleasant | United States |
| USMTU | Matanuska | United States |
| USMTV | Martinsville | United States |
| USMTW | Manitowoc | United States |
| USMTX | Memphis | United States |
| USMTY | Metzger | United States |
| USMTZ | Mantee | United States |
| USMUA | Matthews | United States |
| USMUB | Muncie | United States |
| USMUC | Murfreesboro | United States |
| USMUD | Mt Dora | United States |
| USMUE | Kamuela | United States |
| USMUF | Mulberry | United States |
| USMUG | Millersburg | United States |
| USMUH | Muleshoe | United States |
| USMUI | Fort Indiantown | United States |
| USMUJ | Mundelein | United States |
| USMUK | Mountain View | United States |
| USMUL | Mountain View | United States |
| USMUM | Mountain Home | United States |
| USMUN | Muncy | United States |
| USMUO | Mountain Home | United States |
| USMUP | Mt Prospect | United States |
| USMUQ | Munster | United States |
| USMUS | Murchison | United States |
| USMUT | Muscatine | United States |
| USMUU | Mt Union | United States |
| USMUV | Mountain Top | United States |
| USMUW | Moulton | United States |
| USMUX | Mamou | United States |
| USMUY | Murray | United States |
| USMUZ | Muscoda | United States |
| USMVA | Mar Vista | United States |
| USMVB | Millersville | United States |
| USMVC | Monroeville | United States |
| USMVD | Maryville | United States |
| USMVE | Montevideo | United States |
| USMVG | Middle Village | United States |
| USMVH | Mt Vernon | United States |
| USMVI | Millville | United States |
| USMVJ | Mossville | United States |
| USMVK | Middleville | United States |
| USMVL | Stowe | United States |
| USMVM | Kayenta | United States |
| USMVN | Mount Vernon | United States |
| USMVO | Montevallo | United States |
| USMVP | Minersville | United States |
| USMVQ | Madisonville | United States |
| USMVR | Malvern | United States |
| USMVT | McVeytown | United States |
| USMVU | Maysville | United States |
| USMVV | Marysville | United States |
| USMVW | Mt Vernon | United States |
| USMVX | Mt Vernon | United States |
| USMVY | Martha's Vineyard | United States |
| USMVZ | McConnelsville | United States |
| USMWA | Marion | United States |
| USMWC | Midway City | United States |
| USMWD | Meadow Lands | United States |
| USMWF | Mt Wolf | United States |
| USMWG | Morgantown | United States |
| USMWH | Moses Lake | United States |
| USMWI | Monroe | United States |
| USMWJ | Mason | United States |