| 3801 | MHWA | MOHAWK ADIRONDACK & NORTHERN RAILRO | | | SCAC4 |
| 3802 | MHWA | Mohawk, Adirondack & Northern R.R. Corp. | | USA | TRAFFIC |
| 3803 | MHWD | MONTROSS HARDWOOD CO INC | | | SCAC4 |
| 3804 | MHWI | MERHOW INDUSTRIES | | | SCAC4 |
| 3805 | MHWK | MOHAWK SERVICES INC | | | SCAC4 |
| 3806 | MHX | The Michael Hoffman Fuel Co. | 1/1943-1/1945; 1/1946 (not listed) | | NAKINA |
| 3807 | MHX | MICHAEL HOFFMAN FUEL CO. | | | PWRC |
| 3808 | MHXI | MUSHIANA TRANSPORT INC | | | SCAC4 |
| 3809 | MHXN | MITCHELL TRANSPORT INC | | | SCAC4 |
| 3810 | MHXO | MH TRANSPORT INC | | | SCAC4 |
| 3811 | MHXP | MILE-HI EXPRESS INC | | | SCAC4 |
| 3812 | MHXQ | MOHSEN TRANSPORTATION INC | | | SCAC4 |
| 3813 | MHXR | MITCHELL EXPRESS | | | SCAC4 |
| 3814 | MHXS | MILLHOUSE EXPRESS LLC | | | SCAC4 |
| 3815 | MHXT | M THREE (M3) TRANSPORT | | | SCAC4 |
| 3816 | MHXU | RWE POWER AG-KRAFTWERK MULHEIM-KARL | | | SCAC4 |
| 3817 | MHY | Metron Aviation, Inc. | | USA | AVCODES |
| 3818 | MHYD | MACHEY | | | SCAC4 |
| 3819 | MHYE | MAHONEY EXPRESS INC | | | SCAC4 |
| 3820 | MHYO | MANITOBA HYDRO | | | SCAC4 |
| 3821 | MHYP | MASOULEH CORP-HYGRADE OIL | | | SCAC4 |
| 3822 | MHYR | MCELHANY TRUCKING | | | SCAC4 |
| 3823 | MHYS | MAHONEY & SONS TRANSPORT INC | | | SCAC4 |
| 3824 | MHZX | Matthieson & Hegeler Zinc Co. | 7/1930-1/1952; eliminated 1/1954 | | NAKINA |
| 3825 | MHZX | Matthieson & Hegeler Zinc Co. | 4/38-1/52 | | NRHS |
| 3826 | MHZX | MATTHIESON & HEGELER ZINC CO. | | | PWRC |
| 3827 | MI | SilkAir (S) Pte. Ltd. | ICAO: SLK, Callsign: Silkair, IATA Prefix: 629, Name changed to SilkAir (SINGAPORE) Pte. Ltd. | SGP | AVCODES |
| 3828 | MI | Mackey International | Callsign: Mackey, | USA | AVCODES |
| 3829 | MI | Freebird Airlines Europe Limited | ICAO: FHM, Callsign: Eurobird, | M | AVCODES |
| 3830 | MI | SilkAir (SINGAPORE) Pte. Ltd. | ICAO: SLK, Callsign: Silkair, IATA Prefix: 629, Merged into Singapore Airlines. Name changed from SilkAir (S) Pte. Ltd. | SGP | AVCODES |
| 3831 | MI | Union Pacific R.R. Co. | added 4/1997; 7/2000-7/2005 | | NAKINA |
| 3832 | MI | Missouri Pacific System | 1/1994; eliminated 4/1997 | | NAKINA |
| 3833 | MI | Missouri Pacific R.R. Co. | 1/1980 | | NAKINA |
| 3834 | MI | Missouri-Illinois R.R. Co. | 10/1957-10/1966 & 1/1975 | | NAKINA |
| 3835 | MI | Minnesota & International Ry. Co. | 4/1938-1/1941 | | NAKINA |
| 3836 | MI | Minnesota & International Ry. Co. | Apr-38 | | NRHS |
| 3837 | MI | Missouri-Illinois R.R. Co. | 10/57-10/66 & 1/75 | | NRHS |
| 3838 | MI | Missouri Pacific R.R. Co. | Jan-80 | | NRHS |
| 3839 | MI | Missouri Pacific System | 1/94; eliminated 4/97 | | NRHS |
| 3840 | MI | Union Pacific R.R. Co. | added 4/97; 7/2000 | | NRHS |
| 3841 | MI | *MINNESOTA & INTERNATIONAL RWY. CO. | | | PWRC |
| 3842 | MI | +UP [MISSOURI PACIFIC; MISSOURI - ILLINOIS RR.] | | | PWRC |
| 3843 | MI | Missouri-Illinois Railroad (Union Pacific Railroad) | | | RSRV |
| 3844 | MI | Missouri-Illinois R.R. Co. | | USA | TRAFFIC |
| 3845 | MIA | Mauria, Société Mauritanienne D'aviation | Callsign: Mauria, | RIM | AVCODES |
| 3846 | MIA | Mauria | | | ICAO1 |
| 3847 | MIA | MID-AMERICAN COACHES INC | | | SCAC4 |
| 3848 | MIAB | MARLEON INTERNATIONAL LLC | | | SCAC4 |
| 3849 | MIAC | MIAMI CRATING CO | | | SCAC4 |
| 3850 | MIAJ | MIOARAS ORIGINAL SILK | | | SCAC4 |
| 3851 | MIAL | MINUTEMAN POWERBOSS | | | SCAC4 |
| 3852 | MIAM | MIAMI TRANSPORT INCORPORATED | | | SCAC4 |
| 3853 | MIAO | MITCHELL CONCESSIONS LTD | | | SCAC4 |
| 3854 | MIAQ | MID ATLANTIC PORT SERVICE | | | SCAC4 |
| 3855 | MIAR | MIDNIGHT OIL COMPANY | | | SCAC4 |
| 3856 | MIAU | MONTEBELLO AG | | CH | BIC |
| 3857 | MIAY | MIDWEST INSURANCE AGENCY INC | | | SCAC4 |
| 3858 | MIB | Meiringen-Innertkirchen-Bahn/Kraftwerk Oberhasli | Real: MIB/KWO, 5km narrow gauge(1000mm), electrified at 1200V= This line used to be a construction railway for the hydro-electric power plant. Later the line was opened to the public and operated by battery cars. In 1977 it was electrified and second-hand cars were bought from OEG in Mannheim(D). | CH | TRAFFIC |
| 3859 | MIB | Kraftwerk Oberhasli (Meiringen-Innertkirchen-Bahn) | | CH | VKM |
| 3860 | MIBA | MACTRAN INC | | | SCAC4 |
| 3861 | MIBF | MD INTERNATIONAL BAJA S DE RL | | | SCAC4 |
| 3862 | MIBG | MACHINECRAFT INC | | | SCAC4 |
| 3863 | MIBI | MITSUBISHI ORE TRANSPORT CO LTD | | | SCAC4 |
| 3864 | MIBL | MILLENNIUM TRUCKING INC | | | SCAC4 |
| 3865 | MIBM | MOVE-IT-BROKERAGE LLC | | | SCAC4 |
| 3866 | MIBP | MONTICELLO FLOORING & LUMBER CO INC | | | SCAC4 |
| 3867 | MIBQ | MAYTRANS INTERNATIONAL CORP | | | SCAC4 |
| 3868 | MIBR | MILLER BROS | | | SCAC1 |
| 3869 | MIBR | M I B TRUCKING INC | | | SCAC4 |
| 3870 | MIBRAG | Mitteldeutsche Braunkohle AG | | D | TRAFFIC |
| 3871 | MIC | Aerolineas de Michoacan | Callsign: Michoacan, | MEX | AVCODES |
| 3872 | MIC | Mint Lineas Aereas, S.L. | IATA: IM, Callsign: Mint Airways, Founded in 2009. Ceased operations on 22 May 2012. | E | AVCODES |
| 3873 | MIC | Michels GmbH & Co. KG | | DE | VKM |
| 3874 | MICB | MID CITIES MOTOR FREIGHT INC | | | SCAC4 |
| 3875 | MICC | MALPICA EXPRESS SA DE CV | | | SCAC4 |
| 3876 | MICD | MICHIGAN CARPET DELIVERY | | | SCAC4 |
| 3877 | MICE | MID-IOWA COOPERATIVE | | | SCAC4 |
| 3878 | MICH | MICHELIN AMERICAS RESEARCH COMPANY | | | SCAC4 |
| 3879 | MICHA | Michalczewski Sp. z o.o. | City: Radom | PL | TRAFFIC |
| 3880 | MICI | MINIC INDUSTRIES LIMITED | | | SCAC4 |
| 3881 | MICK | MICKY TRANSPORT LTD | | | SCAC4 |
| 3882 | MICM | MINCHEM INTERNATIONAL INC | | | SCAC4 |
| 3883 | MICN | MEDINA LODI INC | | | SCAC4 |
| 3884 | MICO | Midland Continental R.R. | 10/1966 | | NAKINA |
| 3885 | MICO | Midland Continental R.R. | Oct-66 | | NRHS |
| 3886 | MICO | MIDLAND CONTINENTAL RAILROAD | | | PWRC |
| 3887 | MICO | MITSUI & CO LTD | | | SCAC4 |
| 3888 | MICP | MISSOURI GAS ENERGY | | | SCAC4 |
| 3889 | MICR | MICHIGAN CENTRAL RAILROAD CO. | | | PWRC |
| 3890 | MICT | MICHIGAN CARTAGE MI-CART INC | | | SCAC4 |
| 3891 | MICU | PAN PACIFIC INTL TRADING GROUP (HK) LTD | | HK | BIC |
| 3892 | MICW | MCS INTERNATIONAL MARINE SERVICES B | | | SCAC4 |
| 3893 | MICX | Mississippi Chemical Corp. | added 10/1972; 1/1975-1/1980; eliminated 10/1981 | | NAKINA |
| 3894 | MICX | Mis Coa, a partnership of Mississippi Chemical Corp. and Coastal Chemical Corp. | added 7/1971; eliminated 10/1972 | | NAKINA |
| 3895 | MICX | Mississippi Chemical Corp. | 1/1952-4/1970; eliminated 7/1971 | | NAKINA |
| 3896 | MICX | Mid-Continent Refining Co. | 8/1920-7/1923 | | NAKINA |
| 3897 | MICX | Mis Coa, a partnership of Mississippi Chemical Corp. and Coastal Chemical Corp. | eliminated 10/72 | | NRHS |
| 3898 | MICX | Mississippi Chemical Corp. | 1/52-4/70 | | NRHS |
| 3899 | MICX | Mississippi Chemical Corp. | added 10/72; 1/75-1/80; eliminated 10/81 | | NRHS |
| 3900 | MICX | *MID-CONTINENT REFINING CO. | | | PWRC |
