| 1901 | IMRN | IMMEDIATE AIR CARGO TRANSIT INC | | | SCAC4 |
| 1902 | IMRO | ITALIAN MOTORS LTD | | | SCAC4 |
| 1903 | IMRR | Illinois & Midland R.R. Inc. | added 7/1996; 7/2000-7/2005 | | NAKINA |
| 1904 | IMRR | Illinois & Midland R.R. Inc. | added 7/96; 7/2000 | | NRHS |
| 1905 | IMRR | ILLINOIS & MIDLAND RAILROAD | | | PWRC |
| 1906 | IMRR | Illinois and Midland Railroad | | | RSRV |
| 1907 | IMRR | ILLINOIS & MIDLAND RAILROAD INC | | | SCAC4 |
| 1908 | IMRR | Illinois and Midland | | USA | TRAFFIC |
| 1909 | IMRS | IMPERIAL XPRESSS MIDLAND ONT | | | SCAC4 |
| 1910 | IMRX | Imperial Refineries Corp. | added 7/1955; 10/1957; eliminated 4/1959 | | NAKINA |
| 1911 | IMRX | Central States Oil Co. | 1/1941-7/1954; eliminated 7/1955 | | NAKINA |
| 1912 | IMRX | Imperial Refineries Co. | 7/1937-4/1938 | | NAKINA |
| 1913 | IMRX | Imperial Refining Co. (Imperial Refineries) | 7/1932-7/1935 | | NAKINA |
| 1914 | IMRX | Imperial Refining Co. | 8/1920-7/1930 | | NAKINA |
| 1915 | IMRX | Imperial Refineries | Apr-38 | | NRHS |
| 1916 | IMRX | Central States Oil Co. | 1/52; eliminated 7/55 | | NRHS |
| 1917 | IMRX | Imperial Refineries Corp. | added 7/55; 10/57 | | NRHS |
| 1918 | IMRX | IMPERIAL REFINERIES CORP. (CENTRAL STATES OIL CO.) | | | PWRC |
| 1919 | IMRZ | IOWA INTERSTATE RAILROAD | | | PWRC |
| 1920 | IMRZ | IOWA INTERSTATE RAILROAD LTD | | | SCAC4 |
| 1921 | IMS | Air Images | Callsign: Images, | GB | AVCODES |
| 1922 | IMSAT | IMSAT SA | | RO | VKM |
| 1923 | IMSD | IINO MARINE SERVICE CO LTD | | | SCAC4 |
| 1924 | IMSE | Impresa Salvatore Esposito | | I | TRAFFIC |
| 1925 | IMSF | ISLAND MARITIME SERVICES INC | | | SCAC4 |
| 1926 | IMSG | IMT-SHIPPING & CHARTERING GMBH | | | SCAC4 |
| 1927 | IMSI | IMPORTACIONES RARAMURI | | | SCAC4 |
| 1928 | IMSJ | IRVINE, MICHAEL STUDIOS INC | | | SCAC4 |
| 1929 | IMSN | IMS OF WESTERN NY | | | SCAC4 |
| 1930 | IMSP | INTERNATIONAL MOTOR SPORTS ASSOCIAT | | | SCAC4 |
| 1931 | IMSQ | I M E E S A | | | SCAC4 |
| 1932 | IMSR | INTEGRATED MARINE SERVICES LLC | | | SCAC4 |
| 1933 | IMSU | IMMOBILIARE STELLA SRL | | I | BIC |
| 1934 | IMSU | IMMOBILIARE STELLA SRL | | | SCAC4 |
| 1935 | IMSV | INTERNATIONAL MOVING SERVICE (I M S | | | SCAC4 |
| 1936 | IMSW | INVENTORY MANAGEMENT SERVICES LLC | | | SCAC4 |
| 1937 | IMSX | IMCO Services, a Division of Halliburton Co. | added 1/1982; eliminated 1/1986 | | NAKINA |
| 1938 | IMSX | IMCO Services, a Division of Halliburton Co. | added 1/82; eliminated 1/86 | | NRHS |
| 1939 | IMSX | *IMCO SERVICES, DIV. OF HALLIBURTON CO. | | | PWRC |
| 1940 | IMSX | *INTERNATIONAL MILL SERVICE | | | PWRC |
| 1941 | IMSX | IMCO Services (International Mill Service) | | | RSRV |
| 1942 | IMSY | INTELLIGENT IMAGING SYSTEMS INC | | | SCAC4 |
| 1943 | IMSZ | INTERMODAL SYSTEMS, INC. | | | PWRC |
| 1944 | IMSZ | Intermodal Systems | | | RSRV |
| 1945 | IMSZ | INTERMODAL SYSTEMS, INC. | | | SCAC4 |
| 1946 | IMT | Imtrec Aviation | Callsign: Imtrec, AOC revoked during 2008. | K | AVCODES |
| 1947 | IMT | Imtrec Aviation | | | ICAO1 |
| 1948 | IMTA | INTERMODEL TRANSPORTATION CORP | | | SCAC4 |
| 1949 | IMTB | (IDMC) INDUSTRIAL MARITIME CARRIERS | | | SCAC1 |
| 1950 | IMTB | INDUSTRIAL MARITIME CARRIERS WORLDW | | | SCAC4 |
| 1951 | IMTC | IRON MULE TRUCKING | | | SCAC4 |
| 1952 | IMTE | IMPORTEX | | | SCAC4 |
| 1953 | IMTI | INTERNATIONAL MACHINE TRANSPORT INC | | | SCAC4 |
| 1954 | IMTJ | IMPERIAL TRANSPORT & LEASING LLC | | | SCAC4 |
| 1955 | IMTK | IRISH MALONE TRUCKING INC | | | SCAC4 |
| 1956 | IMTL | IMMORTAL SERVICE INC | | | SCAC4 |
| 1957 | IMTQ | INTERMOUNTAIN TRUCKING LTD | | | SCAC4 |
| 1958 | IMTT | IMH TRANSPORT | | | SCAC4 |
| 1959 | IMTU | ITALIA MARITTIMA S.P.A | | I | BIC |
| 1960 | IMTU | LLOYD TRIESTINO DE NAVIGAZIONE SPA | | | SCAC4 |
| 1961 | IMTV | IMPERIAL ROYAL TOURS INC | | | SCAC4 |
| 1962 | IMTW | INTERNATIONAL MACHINE TRANSPORT USA | | | SCAC4 |
| 1963 | IMTX | Ag Processing, Inc. | added 10/1995; 7/2000-7/2005; eliminated 10/2006 | | NAKINA |
| 1964 | IMTX | AGP, L.P. | added 4/1992; 1/1994; eliminated 10/1995 | | NAKINA |
| 1965 | IMTX | Multifoods Transportation, Inc. | added 7/1980; eliminated 4/1992 | | NAKINA |
| 1966 | IMTX | Missouri Tank Car Corp. | 7/1930-1/1950 | | NAKINA |
| 1967 | IMTX | Missouri Tank Car Corp. | Apr-38 | | NRHS |
| 1968 | IMTX | Multifoods Transportation, Inc. | added 7/80; eliminated 4/92 | | NRHS |
| 1969 | IMTX | AGP, L.P. | added 4/92; 1/94; eliminated 10/95 | | NRHS |
| 1970 | IMTX | Ag Processing, Inc. | added 10/95; 7/2000 | | NRHS |
| 1971 | IMTX | *MISSOURI TANK CAR CORP. | | | PWRC |
| 1972 | IMTX | +AGP, L.P. (AG PROCESSING, INC) [MULTIFOODS TRANSPORTATION INC.] | | | PWRC |
| 1973 | IMTX | Multifoods Transportation (AG Processing) | | | RSRV |
| 1974 | IMV | Industrija motornih vozil | | YU | TRAFFIC |
| 1975 | IMVC | IRISH MOVING & STORAGE INC | | | SCAC4 |
| 1976 | IMWQ | INTERNATIONAL MOVING & STORAGE | | | SCAC4 |
| 1977 | IMWS | INTERMODAL WEST INC | | | SCAC4 |
| 1978 | IMWU | IMWATER TREATMENT PLANTS S.L | | E | BIC |
| 1979 | IMWX | Missouri Valley Walnut Co. | added 7/1976; 1/1980; eliminated 1/1982 | | NAKINA |
| 1980 | IMWX | Transportation Management, Inc. | 1/1975; added 4/1975; eliminated 7/1976 | | NAKINA |
| 1981 | IMWX | Transportation Management, Inc. | 1/75; added 4/75 | | NRHS |
| 1982 | IMWX | Missouri Valley Walnut Co. | 1/80; eliminated 1/82 | | NRHS |
| 1983 | IMWX | *TRANSPORTATION MANAGEMENT, INC. | | | PWRC |
| 1984 | IMWX | *MISSOURI VALLEY WALNUT CO. | | | PWRC |
| 1985 | IMX | Zimex Aviation Limited | IATA: C4, Callsign: Zimex, IATA designator changed from MF | CH | AVCODES |
| 1986 | IMX | Zimex Aviation Limited | IATA: MF, Callsign: Zimex, IATA designator changed to C4* | CH | AVCODES |
| 1987 | IMX | Zimex Aviation Limited | IATA: XM, Callsign: Zimex, IATA Prefix: 927, IATA designator changed from C4* | CH | AVCODES |
| 1988 | IMX | Zimex Aviation | IATA: C4 | | ICAO1 |
| 1989 | IMXA | INTER MEXICANA DE TRANSPORTE S A DE | | | SCAC4 |
| 1990 | IMXH | IMMEDIATE TRANSPORTATION SOLUTIONS | | | SCAC4 |
| 1991 | IMXI | IMEX IMPORT & EXPORT CARTAGE LTD | | | SCAC4 |
| 1992 | IMXK | IMEX MARKETING INC | | | SCAC4 |
| 1993 | IMXO | INTERRUPTORES DE MEXICO S A DE C | | | SCAC4 |
| 1994 | IMXR | IMEX ROZON TRANSPORT INC | | | SCAC4 |
| 1995 | IMXT | IMEX TRANSPORT | | | SCAC4 |
| 1996 | IMXZ | INTERMODAL EXPRESS, INC. | | | PWRC |
| 1997 | IMXZ | Intermodal Express | | | RSRV |
| 1998 | IMXZ | INTERMODAL EXPRESS, INC. | | | SCAC4 |
| 1999 | IN | Makedonski Aviotransport-Macedonian Airlines | ICAO: MAK, Callsign: Makavio, IATA Prefix: 367, Ceased operations on 01 September 2009 after AOC revoked. Established on 16 January 1994. Commenced operations on 23 June 1994. | MK | AVCODES |
| 2000 | IN | Aerlinte Eireann | Callsign: Shamrock, | IRL | AVCODES |
