| 1 | MAC | Malta Air Charter Company Limited | IATA: R5, Callsign: Malta Charter, Designator R5 recalled by IATA | M | AVCODES |
| 2 | MAC | Malta Air Charter Company Limited | Callsign: Malta Charter, Designator R5 recalled by IATA | M | AVCODES |
| 3 | MAC | Air Arabia Maroc | IATA: 3O, Callsign: Nawras, IATA Prefix: 452, ICAO callsign changed to Arabia Maroc | MA | AVCODES |
| 4 | MAC | Air Arabia Maroc | IATA: 3O, Callsign: Arabia Maroc, IATA Prefix: 452, ICAO callsign changed from Nawras | MA | AVCODES |
| 5 | MAC | Malta Air Charter | IATA: R5 | | ICAO1 |
| 6 | MAC | MID AMERICAN CAR | | | PWRC |
| 7 | MAC | MIDDLE ATLANTIC CONFERENCE, AGENT | | | SCAC4 |
| 8 | MACD | McDONALD'S EXPRESS LINE, INC | | | SCAC1 |
| 9 | MACEG | MACEG S.r.l. - Construzioni Generali Edili e Ferroviarie | | I | TRAFFIC |
| 10 | MACF | MODULAR AND CUSTOM CABINETS | | | SCAC4 |
| 11 | MACI | MONTANA AIR CARTAGE INC | | | SCAC4 |
| 12 | MACJ | MACCAULEY | | | SCAC4 |
| 13 | MACK | MACKENZIE TRUCKING INC | | | SCAC4 |
| 14 | MACL | MACK OIL COMPANY INC | | | SCAC4 |
| 15 | MACO | McCormick, Ashland City & Nashville R.R. Inc. | added 10/1988; eliminated 1/1993 | | NAKINA |
| 16 | MACO | McCormick, Ashland City & Nashville R.R. Inc. | added 10/88; eliminated 1/93 | | NRHS |
| 17 | MACO | RETIRED 07-28-93 ATP (370) ATP [MCCORMICK-ASHLAND CITY & NASHVILLE RR} | | | PWRC |
| 18 | MACO | MAC LOGISTICS INC | | | SCAC4 |
| 19 | MACQ | MERCURY AIR CARGO INC | | | SCAC4 |
| 20 | MACR | Minneapolis, Anoka and Cuyuna Range R.R. Co. | 1/1975 | | NAKINA |
| 21 | MACR | Minneapolis, Anoka and Cuyuna Range R.R. Co. | Jan-75 | | NRHS |
| 22 | MACR | MINNEAPOLIS, ANOKA AND CUYUNA RANGE RAILROAD CO. | | | PWRC |
| 23 | MACR | MACRO TRANSPORT SERVICES LLC | | | SCAC4 |
| 24 | MACT | MAICOT INTERNATIONAL FREIGHT LLC | | | SCAC4 |
| 25 | MACU | ADR TRASPORTI SRL | | I | BIC |
| 26 | MACU | MAS CONSOLIDATE (PVT) LTD | | | SCAC4 |
| 27 | MACW | MACWORTH TRANSPORTATION SERVICES IN | | | SCAC4 |
| 28 | MACX | Mac Acquisitions, L.P. | added 10/1996; 7/2000-7/2005 | | NAKINA |
| 29 | MACX | Fruehauf Corp. | added 11/1973; 1/1975-1/1980; eliminated 7/1983 | | NAKINA |
| 30 | MACX | Magor Railcar Division, Fruehauf Corp. | eliminated 11/1973 | | NAKINA |
| 31 | MACX | Fruehauf Railcar Division, Fruehauf Corp. | added 7/1970 | | NAKINA |
| 32 | MACX | Magor Railcar Division, Fruehauf Corp. | added 7/1968; 4/1970; eliminated 7/1970 | | NAKINA |
| 33 | MACX | Magor Car Corp. | added 7/1961; 7/1965-10/1966; eliminated 10/1967 | | NAKINA |
| 34 | MACX | Mahaffey Commission Co. | 7/1935 | | NAKINA |
| 35 | MACX | Magor Car Corp. | 7/65-10/66; eliminated 10/67 | | NRHS |
| 36 | MACX | Magor Railcar Division, Fruehauf Corp. | added 7/68; 4/70 | | NRHS |
| 37 | MACX | Fruehauf Corp. | 1/75-1/80 | | NRHS |
| 38 | MACX | Mac Acquisitions, L.P. | added 10/96; 7/2000 | | NRHS |
| 39 | MACX | *MAGOR RAILCAR DIV., FRUEHOF CORP. | | | PWRC |
| 40 | MACX | +MAC ACQUISITIONS. L.P. | | | PWRC |
| 41 | MACX | Mac Acquisitions | | | RSRV |
| 42 | MACX | MAC ACQUISITIONS L P | | | SCAC4 |
| 43 | MACY | MACROWAY INC | | | SCAC4 |
| 44 | MACZ | MARYLAND ASSOCIATION OF RAIL COMMUTERS | | | PWRC |
