| Abbreviation | Definition |
|---|---|
| MTW | Marinette, Tomahawk and Western Railroad |
| MTYU | Seacube Container Leasing |
| MTZ | Mitsui O. S. K. Lines Limited |
| MTZ | Mitsui O.S.K. Lines |
| MURL | Melbourne Underground Rail Loop |
| MUSC | Memphis Union Station |
| MUSC | Memphis Union Station Company |
| MV | Midland Valley Railroad |
| MVCX | Chaparral Energy |
| MVP | Missouri and Valley Park Railroad |
| MVRS | Mystic Valley Railway Society |
| MVRY | Mahoning Valley Railway |
| MVRY | Mahoning Valley Railway Company |
| MVT | Mount Vernon Terminal |
| MVT | Mt. Vernon Terminal |
| MW&S | Maintenance of Way and Structures |
| MWAX | Martin Marietta Materials |
| MWAX | Martin Marietta Materials Incorporated |
| MWBX | Midwest By-Products |
| MWCL | Midwest Coal Handling |