| 1 | MPL | Master Planner, Inc. | | USA | AVCODES |
| 2 | MPL | Metropolitan Airways Ltd. | Callsign: Metro, | GB | AVCODES |
| 3 | MPL | Master Planner | | | ICAO1 |
| 4 | MPL | MISSISSIPPI POWER & LIGHT | | | PWRC |
| 5 | MPL | MORIS Sp. z o.o. | | PL | VKM |
| 6 | MPLB | M & P LOGISTICS I, LP | | | SCAC4 |
| 7 | MPLD | MONTREAL PIPE LINE LIMITED | | | SCAC4 |
| 8 | MPLF | M & P LOGISTICS LLC | | | SCAC4 |
| 9 | MPLG | MAPLES GAS CO INC | | | SCAC4 |
| 10 | MPLH | MERTENS, PAUL H | | | SCAC4 |
| 11 | MPLI | Minnesota Prairie Line Inc. | added 10/2002; 7/2005 | | NAKINA |
| 12 | MPLI | MINNESOTA PRAIRIE LINE, INC. | | | PWRC |
| 13 | MPLI | Minnesota Prairie Line | | | RSRV |
| 14 | MPLI | MINNESOTA PRAIRIE LINE INC | | | SCAC4 |
| 15 | MPLK | MOSAIC PLANET | | | SCAC4 |
| 16 | MPLM | MP LINE DE MEXICO SA DE CV | | | SCAC4 |
| 17 | MPLN | M P L MFG INC | | | SCAC4 |
| 18 | MPLO | MARTIN PALLET INC | | | SCAC4 |
| 19 | MPLQ | MAPLE TRANSPORTATION LLC | | | SCAC4 |
| 20 | MPLR | MASTERPIECE INTERNATIONAL LIMITED | | | SCAC4 |
| 21 | MPLT | MILLER, PAUL TRUCKING INC | | | SCAC4 |
| 22 | MPLW | MOVING PERFORMANCE LLC | | | SCAC4 |
| 23 | MPLX | General Electric Railcar Services Corp. | added 1/1984; 1/1994; eliminated 10/1994 | | NAKINA |
| 24 | MPLX | North American Car Corp. | added 4/1973; 1/1975-1/1980; eliminated 1/1984 | | NAKINA |
| 25 | MPLX | Marhoefer Packing Co., Inc. | added 1/1969 | | NAKINA |
| 26 | MPLX | American Oil Co. | added 10/1954; 10/1957; eliminated 4/1961 | | NAKINA |
| 27 | MPLX | Mexican Petroleum Corp. | 7/1923-7/1954; eliminated 10/1954 | | NAKINA |
| 28 | MPLX | Mexican Petroleum Co. (Mexican Petroleum Corp.) | 8/1920 | | NAKINA |
| 29 | MPLX | Mexican Petroleum Corp. | 4/38-1/52 | | NRHS |
| 30 | MPLX | American Oil Co. | 10/57; eliminated 4/61 | | NRHS |
| 31 | MPLX | Marhoefer Packing Co., Inc. | added 1/69 | | NRHS |
| 32 | MPLX | North American Car Corp. | added 4/73; 1/75-1/80 | | NRHS |
| 33 | MPLX | General Electric Railcar Services Corp. | 1/94; eliminated 10/94 | | NRHS |
| 34 | MPLX | *AMERICAN OIL CO [MEXICAN PETROLEUM CORP.] | | | PWRC |
| 35 | MPLX | *MARHOEFER PACKING CO., INC. | | | PWRC |
| 36 | MPLX | *(NATX) G. E. RAILCAR SERVICES CORP. [MOUNTAIN PINE LUMBER LTD.] | | | PWRC |
| 37 | MPLX | GE Rail Services | | | RSRV |
| 38 | MPLZ | *MINNESOTA POWER & LIGHT CO. | | | PWRC |
| 39 | MPLZ | *UNION PACIFIC RAILROAD COMPANY | | | PWRC |
| 40 | MPLZ | Missouri Pacific Railroad (Union Pacific Railroad) | | | RSRV |
