| 1 | MC | Air Mobility Command (AMC) | ICAO: RCH, Callsign: Reach, | USA | AVCODES |
| 2 | MC | Air Mobility Command | ICAO: USM, | USA | AVCODES |
| 3 | MC | Civil Aviation Authority Flying Unit | ICAO: CFU, Callsign: Minair, Designator MC recalled by IATA | GB | AVCODES |
| 4 | MC | Maine Coast R.R. Corp. | added 10/1992; eliminated 10/1993; 1/1994 (not listed); eliminated 1/1997; added 10/1999; 7/2000; eliminated 7/2002 | | NAKINA |
| 5 | MC | Michigan Central R.R. | 1/1975 | | NAKINA |
| 6 | MC | Consolidated Rail Corp. | 1/1980 | | NAKINA |
| 7 | MC | Michigan Central R.R. | Jan-75 | | NRHS |
| 8 | MC | Consolidated Rail Corp. | Jan-80 | | NRHS |
| 9 | MC | Maine Coast R.R. Corp. | added 10/92; eliminated 10/93; 1/94; eliminated 1/97; added 10/99; 7/2000 | | NRHS |
| 10 | MC | *NORFOLK SOUTHERN [CONRAIL; PENN CENTRAL; NEW YORK CENTRAL; MICHIGAN CENTRAL RR] | | | PWRC |
| 11 | MC | *MAINE COAST RAILROAD CORPORATION | | | PWRC |
| 12 | MC | +MASSACHUSETTS COASTAL RAILROAD LLC | | | PWRC |
| 13 | MC | Michigan Central Railroad (Massachusetts Coastal Railroad) | | | RSRV |
| 14 | MC | MASSACHU | | | SCAC4 |
| 15 | MC | MassCentral | | USA | TRAFFIC |
| 16 | MC&S | Moscow, Camden & San Augustine R.R. | 7/1923-4/1938 | | NAKINA |
| 17 | MC&S | Moscow, Camden & San Augustine R.R. | Apr-38 | | NRHS |
| 18 | MC&S | MOSCOW, CAMDEN & SAN AUGUSTINE RAILROAD | | | PWRC |
| 19 | MCA | Midcontinent Airlines, Inc. | Callsign: Heartland, ICAO callsign changed from Continair | USA | AVCODES |
| 20 | MCA | MCA Airlines Sweden AB | Callsign: Calson, | S | AVCODES |
| 21 | MCA | Muse Air Corp | Callsign: Muase Air, | USA | AVCODES |
| 22 | MCA | Midcontinent Airlines, Inc. | Callsign: Continair, ICAO callsign changed to Heartland | USA | AVCODES |
| 23 | MCA | Mediterranean Coastal Airlines Ltd. | Callsign: Coastal Clipper, | M | AVCODES |
| 24 | MCAE | MCENENY STABLE | | | SCAC4 |
| 25 | MCAF | MCARTHUR, DENNIS TRANSPORT | | | SCAC4 |
| 26 | MCAG | MAC-AGG SUPPLY INC | | | SCAC4 |
| 27 | MCAH | MCD EXPRESS INC | | | SCAC4 |
| 28 | MCAI | MOTOR CARTAGE | | | SCAC4 |
| 29 | MCAJ | MCAFEE, M J DISTRIBUTING INC USA | | | SCAC4 |
| 30 | MCAM | MUSKINGU | | | SCAC4 |
| 31 | MCAN | MONARCH CARRIERS INC | | | SCAC4 |
| 32 | MCAO | MCCONNELL TRANSPORT INC | | | SCAC4 |
| 33 | MCAR | Metrocars | City: St. Louis | F | TRAFFIC |
| 34 | MCAS | MACA SUPPLY COMPANY | | | SCAC4 |
| 35 | MCAT | MCALEXANDE | | | SCAC4 |
| 36 | MCAU | MAERSK A/S | | DK | BIC |
| 37 | MCAU | A P MOLLER | | | SCAC4 |
| 38 | MCAX | North American Car Corp. | added 7/1955; 10/1957-1/1975; eliminated 4/1975 | | NAKINA |
| 39 | MCAX | Mather Stock Car Co. | 7/1937-7/1954; eliminated 7/1955 | | NAKINA |
| 40 | MCAX | Mather Stock Car Co. | 4/38-1/52; eliminated 7/55 | | NRHS |
| 41 | MCAX | North American Car Corp. | added 7/55; 10/57-1/75; eliminated 4/75 | | NRHS |
| 42 | MCAX | (NATX) NORTH AMERICAN CAR CORP [MATHER STOCK CAR CO.] (NCCo) | | | PWRC |
| 43 | MCAY | MCNAY, RICHARD INC | | | SCAC4 |
| 44 | MCB | Tbilisi State Aviation Corporation | | UA | AVCODES |
| 45 | MCB | Air Mercia | Callsign: Westmid, Ceased operations. | GB | AVCODES |
| 46 | MCB | Air Mercia | | | ICAO1 |
| 47 | MCBD | MERCER TRANSPORTATION CO INC (BROKE | | | SCAC4 |
| 48 | MCBH | MARCUS & CO ESTATE BUYERS INC | | | SCAC4 |
| 49 | MCBI | MONTALCO CABINETS LTD | | | SCAC4 |
| 50 | MCBJ | MR BILLS COMMON CONTRACT CARRIER IN | | | SCAC4 |
| 51 | MCBK | MCB TRUCKING INC | | | SCAC4 |
| 52 | MCBR | MCBRIDE TRUCKING | | | SCAC4 |
| 53 | MCBU | MOELLER CHEMIE GMBH & CO. KG | | D | BIC |
| 54 | MCBY | MCBRAYER TRUCKING | | | SCAC4 |
| 55 | MCC | Aerocom | | MD | AVCODES |
| 56 | MCC | MCC Aviation | | ZA | AVCODES |
| 57 | MCC | MCC Aviation | | | ICAO1 |
| 58 | MCC | MORRIC COUNTY CENTRAL | | | PWRC |
| 59 | MCCC | MILLER, CHRIS C | | | SCAC4 |
| 60 | MCCD | McCARTHY DRAYING CO | | | SCAC1 |
| 61 | MCCD | MCCARTHY DRAYING COMPANY | | | SCAC4 |
| 62 | MCCE | MCMILLAN CRANE SERVICE INC | | | SCAC4 |
| 63 | MCCG | MCCOLLISTERS TRANSPORTATION SYSTEMS | | | SCAC4 |
| 64 | MCCH | MCCONCHIE TRUCKING LTD | | | SCAC4 |
| 65 | MCCI | MEMPHIS CITY CARTAGE INC | | | SCAC4 |
| 66 | MCCJ | MCCULLAGH, J | | | SCAC4 |
| 67 | MCCK | MCCLINTOCK INCORPORATED | | | SCAC4 |
| 68 | MCCL | MASON CITY & CLEAR LAKE ELECTRIC RAILWAY HISTORICAL SOCIETY | | | PWRC |
| 69 | MCCO | MOBILE CHEMICAL CO. | | | PWRC |
| 70 | MCCO | MCCORMICK AND MCCORMICK INC | | | SCAC4 |
| 71 | MCCP | MUSKOGEE CITY-COUNTY PORT AUTHORITY | | | PWRC |
| 72 | MCCP | MCCOPIER CANADA INC | | | SCAC4 |
| 73 | MCCQ | MCC TRANSPORT SINGAPORE PTE LTD | | | SCAC4 |
| 74 | MCCS | MARNA CONSTRUCTION LTD | | | SCAC4 |
| 75 | MCCT | MOSHER, C & C TRUCKING LLC | | | SCAC4 |
| 76 | MCCU | MAXON C&T CORPORATION LIMITED | | HK | BIC |
| 77 | MCCX | Mt. Vernon Transfer Terminal, LLC | added 10/2000; eliminated 7/2002; 7/2005 (not listed) | | NAKINA |
| 78 | MCCX | Mt. Vernon Coal Transfer Co. | added 1/1983; 1/1994-7/2000; eliminated 10/2000 | | NAKINA |
| 79 | MCCX | Madison Coal Corp. | 4/1961 | | NAKINA |
| 80 | MCCX | Mutual Chemical Division, Allied Chemical & Dye Corp. | eliminated 7/1958 | | NAKINA |
| 81 | MCCX | Madison Coal Corp. | added 1/1961; eliminated 7/1963 | | NAKINA |
| 82 | MCCX | Mutual Chemical Division, Allied Chemical and Dye Corp. | added 7/1955; 10/1957 | | NAKINA |
| 83 | MCCX | Mutual Chemical Co. of America | 7/1937-7/1954; eliminated 7/1955 | | NAKINA |
| 84 | MCCX | Mutual Chemical Co. of America | 4/38-1/52; eliminated 7/55 | | NRHS |
| 85 | MCCX | Mutual Chemical Division, Allied Chemical and Dye Corp. | added 7/55; 10/57 | | NRHS |
| 86 | MCCX | Madison Coal Corp. | eliminated 7/63 | | NRHS |
| 87 | MCCX | Mutual Chemical Division, Allied Chemical & Dye Corp. | eliminated 7/58 | | NRHS |
| 88 | MCCX | Madison Coal Corp. | Apr-61 | | NRHS |
| 89 | MCCX | Mt. Vernon Coal Transfer Co. | added 1/83; 1/94-7/2000; eliminated 10/2000 | | NRHS |
| 90 | MCCX | Mt. Vernon Transfer Terminal, LLC | added 10/2000 | | NRHS |
| 91 | MCCX | *MUTUAL CHEMICAL DIV., ALLIED CHEMICAL & DYE CORP. | | | PWRC |
| 92 | MCCX | *MADISON COAL CORP. | | | PWRC |
| 93 | MCCX | +MT. VERNON TRANSFER TERMINAL, LLC [MT. VERNON COAL TRANSFER CO.] | | | PWRC |
| 94 | MCCX | Mount Vernon Coal Transfer | | | RSRV |
| 95 | MCCX | MT VERNON TRANSFER TERMINAL LLC | | | SCAC4 |
| 96 | MCCZ | MORTON CHEMICAL CO. | | | PWRC |
| 97 | MCD | Air Medical Ltd. | Callsign: Air Med, Ceased operations on 01 February 2016. | GB | AVCODES |
| 98 | MCD | Air Medical | | | ICAO1 |
| 99 | MCDA | MCD TRANSPORTATION INC S DE RL | | | SCAC4 |
| 100 | MCDC | MCD AIR TRANSPORT INC | | | SCAC4 |
