| 1901 | MDBW | MID-ATLANTIC INTERNATIONAL FREIGHT | | | SCAC4 |
| 1902 | MDC | Atlantic Aero, Inc. d/b/a Atlantic Aero And Mid-Atlantic Freight | Callsign: Night Ship, | USA | AVCODES |
| 1903 | MDC | Atlantic Aero and Mid-Atlantic Freight | | | ICAO1 |
| 1904 | MDCC | MID-COLUMBIA CHARTERS INC | | | SCAC4 |
| 1905 | MDCH | MERRITT, DONALD C | | | SCAC4 |
| 1906 | MDCL | MACDONALD CARTAGE LTD | | | SCAC4 |
| 1907 | MDCN | MID CONTINENT TRUCKING COMPANY | | | SCAC4 |
| 1908 | MDCO | MID-ATLANTIC LEASING CORP | | | SCAC4 |
| 1909 | MDCR | MIDLAND TERMINAL COMPANY | | | PWRC |
| 1910 | MDCR | MIDLAND COURIER SERVICES, INC | | | SCAC1 |
| 1911 | MDCU | MEDLOG (SHANGHAI) CO.,LTD. | | PRC | BIC |
| 1912 | MDCW | MID-CONTINENT COAL AND COKE | | | SCAC4 |
| 1913 | MDCX | Mexicana de Cobre, S.A. de C.V. | added 7/1989; 1/1994-7/2005; eliminated 1/2006 | | NAKINA |
| 1914 | MDCX | Middleboro Chemical Industries, Inc. | 4/1970; added 7/1971; eliminated 1/1972 | | NAKINA |
| 1915 | MDCX | Middleboro Chemical Industries, Inc. | 4/70; eliminated 1/72 | | NRHS |
| 1916 | MDCX | Mexicana de Cobre, S.A. de C.V. | added 7/89; 1/94-7/2000 | | NRHS |
| 1917 | MDCX | *MIDDLEBORO CHEMICAL INDUSTRIES, INC. | | | PWRC |
| 1918 | MDCX | +MEXICANA DE COBRE SA DE CV [MEXICANA DE ACIDO SULFURICO, SA DE CV] | | | PWRC |
| 1919 | MDCX | Mexicana De Cobre de CV | | | RSRV |
| 1920 | MDCX | MEXICANA DE COBRE SA DE CV | | | SCAC4 |
| 1921 | MDD | MDA Airlines, Joint-Stock Company | Callsign: Donlines, | RUS | AVCODES |
| 1922 | MDD | MDLR Airlines Pvt. Ltd. | IATA: 9Y, | IND | AVCODES |
| 1923 | MDD | Air Maryland | Callsign: Air Maryland, | USA | AVCODES |
| 1924 | MDD | | | USA | TRAFFIC |
| 1925 | MDDA | MUEBLES DE DISENO ANDALUCIA | | | SCAC4 |
| 1926 | MDDB | MICROBRASS | | | SCAC4 |
| 1927 | MDDE | Maryland and Delaware R.R. Co. | added 1/1978; 1/1980; eliminated 10/1987; 1/1994-7/2005; eliminated 10/2009 | | NAKINA |
| 1928 | MDDE | Maryland and Delaware R.R. Co. | added 1/78; 1/80; eliminated 10/87; 1/94-7/2000 | | NRHS |
| 1929 | MDDE | MARYLAND & DELAWARE RAILROAD CO. | | | PWRC |
| 1930 | MDDE | Maryland and Delaware Railroad | | | RSRV |
| 1931 | MDDH | M & D TRANSPORTATION LLC | | | SCAC4 |
| 1932 | MDDK | MADDOCK, ROGER, TRANSPORTATION | | | SCAC1 |
| 1933 | MDDL | MANDERS DIESEL REPAIR INC | | | SCAC4 |
| 1934 | MDDM | M & D LLC | | | SCAC4 |
| 1935 | MDDN | MADDEN OIL COMPANY | | | SCAC4 |
| 1936 | MDDO | METAL DYNAMICS DETROIT LLC | | | SCAC4 |
| 1937 | MDDR | MIDLAND DIRECT INC | | | SCAC4 |
| 1938 | MDDX | Old Line Holding Co., Inc. | 7/2000; eliminated 10/2004; 7/2005 (not listed) | | NAKINA |
| 1939 | MDDX | Old Line Holding Co., Inc. | Jul-00 | | NRHS |
| 1940 | MDDX | OLD LINE HOLDINGS COMPANY INC. | | | PWRC |
| 1941 | MDDX | Old Line Holding | | | RSRV |
| 1942 | MDDY | MITCHELL, D | | | SCAC4 |
| 1943 | MDE | Mauritanienne de Transport Aerien | Callsign: Mauri-Trans, | RIM | AVCODES |
| 1944 | MDE | Mauritanienne De Transport Aerien | | | ICAO1 |
| 1945 | MDE | MANTENIMIENTO DE ESTACIONES, S.L. | | ES | VKM |
| 1946 | MDEA | MEDINA TRANSPORTATION | | | SCAC4 |
| 1947 | MDEB | MIDNITE EXPRESS INC | | | SCAC4 |
| 1948 | MDED | MD ENTERPRISE | | | SCAC4 |
| 1949 | MDEF | Ministerio de Defensa - DISAR | | ES | VKM |
| 1950 | MDEH | MID WEST EXPRESS INC | | | SCAC4 |
| 1951 | MDEI | MT EMPIRE ENTERPRISES INC | | | SCAC4 |
| 1952 | MDEJ | MEDITERRANEO LINE | | | SCAC4 |
| 1953 | MDEK | MERCED | | | SCAC4 |
| 1954 | MDEL | M D EXPRESS LTD | | | SCAC4 |
| 1955 | MDEM | MIDDLE TENNESSEE LUMBER CO INC | | | SCAC4 |
| 1956 | MDEQ | M D EXPRESS | | | SCAC4 |
| 1957 | MDER | M DERICK TRANSPORT | | | SCAC4 |
| 1958 | MDET | MID-EAST TRUCK & TRACTOR SERVICE IN | | | SCAC4 |
| 1959 | MDEU | MINISTERE DES ARMEES - CSOA | | F | BIC |
| 1960 | MDEU | CENTRE MULTIMODAL DES TRANSPORTS | | | SCAC4 |
| 1961 | MDEV | MDE TRANSPORTATION LLC | | | SCAC4 |
| 1962 | MDEY | MEDICACCES | | | SCAC4 |
| 1963 | MDF | Mediterranean Air Freight A.E. | Callsign: Med-Freight, Name changed to Swiftair Hellas S.A. Established in 2002. Commenced operations in June 2003. | GR | AVCODES |
| 1964 | MDF | Midtfly ApS | Callsign: Midfly, | DK | AVCODES |
| 1965 | MDF | Swiftair Hellas S.A. | Callsign: Med-Freight, Name changed from Mediterranean Air Freight A.E. Established in 2002. Commenced operations in June 2003. Wholly owned by Swiftair, S.A. (SWT) | GR | AVCODES |
| 1966 | MDF | Mediterranean Air Freight | | | ICAO1 |
| 1967 | MDFB | M D F INC | | | SCAC4 |
| 1968 | MDFD | MD CARRIERS INC | | | SCAC4 |
| 1969 | MDFE | MIDDLEFIELD ROAD EQUIPMENT LIMITED | | | SCAC4 |
| 1970 | MDFG | M & D FREIGHT LLC | | | SCAC4 |
| 1971 | MDFL | MODERN FORWARDING & LEASING CO INC | | | SCAC4 |
| 1972 | MDFM | MODERN LANDFILL INC | | | SCAC4 |
| 1973 | MDFU | NAVIGAZIONE SAN PAULO (MEDAFRICA) | | | SCAC3 |
| 1974 | MDFW | MDS FREIGHT & TRADING CO LTD | | | SCAC4 |
| 1975 | MDFX | Merchants Despatch Transportation Co. | added 1/1962; eliminated 1/1963 | | NAKINA |
| 1976 | MDFX | Merchants Despatch Transportation Co. | added 1/62 | | NRHS |
| 1977 | MDFX | MERCHANTS DESPATCH TRANSPORTATION CO. | | | PWRC |
| 1978 | MDFY | MED ROOFING SUPPLY INC | | | SCAC4 |
| 1979 | MDG | Air Madagascar | IATA: MD, Callsign: Air Madagascar, IATA Prefix: 258, ICAO callsign changed from Madair | RM | AVCODES |
| 1980 | MDG | Air Madagascar | IATA: MD, Callsign: Madair, IATA Prefix: 258, ICAO callsign changed to Air Madagascar | RM | AVCODES |
| 1981 | MDG | Air Madagascar | IATA: MD | | ICAO1 |
| 1982 | MDGA | MID-GA COURIER INC | | | SCAC4 |
| 1983 | MDGE | MAD DOG EXPRESS COMPANY INC | | | SCAC4 |
| 1984 | MDGG | MIDATLANTIC LEASING | | | SCAC4 |
| 1985 | MDGH | MDX TRANSPORT INC | | | SCAC4 |
| 1986 | MDGI | MAKRO DENIZCILIK VE GEMI | | | SCAC4 |
| 1987 | MDGJ | MARINELAND LOGISTICS INC | | | SCAC4 |
| 1988 | MDGK | MILLER, DOUG TRUCKING | | | SCAC4 |
| 1989 | MDGL | M & D LOGISTICS LLC | | | SCAC4 |
| 1990 | MDGN | MADIGAN LIME | | | SCAC4 |
| 1991 | MDGO | MADRIGRANO TRUCK LINES INC | | | SCAC4 |
| 1992 | MDGP | MARTINEZ DOMINGUEZ, PABLO | | | SCAC4 |
| 1993 | MDGQ | MIDNITE LOGISTICS INC | | | SCAC4 |
| 1994 | MDGW | MECCA, D G & SONS LLC | | | SCAC4 |
| 1995 | MDGY | MDI YACHT TRANSPORT LLC | | | SCAC4 |
| 1996 | MDH | Madina Air | IATA: 3Y, IATA Prefix: 022, | LAR | AVCODES |
| 1997 | MDH | Madina Air | | | ICAO1 |
| 1998 | MDHE | MARTIN, DAVID H EXCAVATING INC | | | SCAC4 |
| 1999 | MDHF | M & D GLOBAL LOGISTICS INC | | | SCAC4 |
| 2000 | MDHG | MDH ENGINEERED SOLUTIONS CORP | | | SCAC4 |
