| 1801 | IMFO | INTERLINE MOTOR FREIGHT ONTARIO INC | | | SCAC4 |
| 1802 | IMFQ | IHUNT MOTOR FREIGHT INC | | | SCAC4 |
| 1803 | IMFS | INTERSTATE MOTOR FRT SYS | | | PWRC |
| 1804 | IMFV | INSTRUMENTOS MUSICALES FENDER SA DE | | | SCAC4 |
| 1805 | IMFX | General American Transportation Corp. | added 7/1971; 1/1975-1/1980; eliminated 10/1992 | | NAKINA |
| 1806 | IMFX | General American Transportation Corp. | 1/75-1/80; eliminated 10/92 | | NRHS |
| 1807 | IMFX | (GATX) RETIRED 08-19-92 ATP (1845) [INTERNATIONAL MULTIFOODS] | | | PWRC |
| 1808 | IMFX | General American Transportation Corporation (GATX) | | | RSRV |
| 1809 | IMG | Imperial Cargo Airlines Limited | Callsign: Imperial Airlines, | GH | AVCODES |
| 1810 | IMG | Imagine Air Jet Services, LLC | Callsign: Imagine, | USA | AVCODES |
| 1811 | IMGA | IMAGE AIR | | | SCAC4 |
| 1812 | IMGB | I MOVE GREEN LLC | | | SCAC4 |
| 1813 | IMGC | IMAGO CORVI | | | SCAC4 |
| 1814 | IMGH | IMAGINE THAT | | | SCAC4 |
| 1815 | IMGI | IMG TRANSPORT INC | | | SCAC4 |
| 1816 | IMGK | IMG TRUCKING INC | | | SCAC4 |
| 1817 | IMGP | INTERMODAL MAINTENANCE GROUP L L C | | | SCAC4 |
| 1818 | IMGT | IMAGE TRANSPORTATION | | | SCAC4 |
| 1819 | IMHZ | INTERMODAL HUB | | | PWRC |
| 1820 | IMI | Imperial Aerotransporte, S.A. de C.V. | Callsign: Imperialaereo, | MEX | AVCODES |
| 1821 | IMID | Indiana Midland Ry. | added 4/1985; eliminated 1/1988 | | NAKINA |
| 1822 | IMID | Indiana Midland Ry. | added 4/85; eliminated 1/88 | | NRHS |
| 1823 | IMID | INDIANA MIDLAND CO. (CODE SUSPENDED 7/27/87) | | | PWRC |
| 1824 | IMIM | IMI MANUFACTURING DE MEXICO SA DE C | | | SCAC4 |
| 1825 | IMIN | INTERNATIONAL MARITIME INC | | | SCAC4 |
| 1826 | IMIP | IMI DEL PERU SAC | | | SCAC4 |
| 1827 | IMIQ | IMASCO MINERALS INC | | | SCAC4 |
| 1828 | IMIU | SULLAIR ARGENTINA S.A. | | RA | BIC |
| 1829 | IMJ | Imperial Jet | | RL | AVCODES |
| 1830 | IMJN | INIGO MUNOZ, JUAN | | | SCAC4 |
| 1831 | IMKC | I MARK CORPORATION | | | SCAC4 |
| 1832 | IMKI | IDAHORAM TRUCKING INC | | | SCAC4 |
| 1833 | IMKN | INTER MARK INC | | | SCAC4 |
| 1834 | IMKU | TRANSPORT COMPANY NC LTD | | | SCAC4 |
| 1835 | IML | Island Air Limited | Callsign: Mal Air, | FJI | AVCODES |
| 1836 | IML | Island Air Limited | IATA: 4M, Callsign: Mal Air, Designator 4M recalled by IATA | FJI | AVCODES |
| 1837 | IMLB | INTASECSHIN MEDIA LLC | | | SCAC4 |
| 1838 | IMLE | IL-MS LLC | | | SCAC4 |
| 1839 | IMLF | IML FREIGHT INC | | | PWRC |
| 1840 | IMLI | INTERMODAL LOGISTICS INC | | | SCAC4 |
| 1841 | IMLL | IMPERIAL MANAGEMENT & LEASING LLC | | | SCAC4 |
| 1842 | IMLM | IMPERIAL LIMOUSINE | | | SCAC4 |
| 1843 | IMLOG | Imbach Logistik AG | | CH | VKM |
| 1844 | IMLR | IMLERS POULTRY TRANSPORTATION INC | | | SCAC4 |
| 1845 | IMLS | INGRAM, WILLIAM J FUELS INC | | | SCAC4 |
| 1846 | IMLU | INTAMODAL S L | | | SCAC4 |
| 1847 | IMM | Marina Militare (Italian Navy) | | I | TRAFFIC |
| 1848 | IMME | IMME TRANSPORT INC | | | SCAC4 |
| 1849 | IMMG | INMAN TRUCKING INC | | | SCAC4 |
| 1850 | IMMU | INDUSTRIAS MONFEL S.A. DE C.V. | | MEX | BIC |
| 1851 | IMMU | Industrias Monfel | | | RSRV |
| 1852 | IMMU | INDUSTRIAS MONDEL S A DE C V | | | SCAC4 |
| 1853 | IMMX | Industrial Minera Mexico, S.A. | added 7/1975; 1/1980; eliminated 5/1983; 1/1994-7/2005 (not listed) | | NAKINA |
| 1854 | IMMX | Industrial Minera Mexico, S.A. | added 7/75; 1/80; eliminated 5/83; 1/94-7/2000 | | NRHS |
| 1855 | IMMX | INDUSTRIAL MINERA MEXICO, SA | | | PWRC |
| 1856 | IMMX | Industrial Minera Mexico | | | RSRV |
| 1857 | IMMX | INDUSTRIAL MINERA MEXICO, S.A. | | | SCAC4 |
| 1858 | IMN | Aerotaxis Cimarron, S.A. de C.V. | Callsign: Taxi Cimarron, | MEX | AVCODES |
| 1859 | IMN | Aerotaxis Cimarron | | | ICAO1 |
| 1860 | IMNA | IMENSA | | | SCAC4 |
| 1861 | IMNS | INTERMODAL MANAGEMENT SYSTEM LLC | | | SCAC4 |
| 1862 | IMNU | Seateq Corporation | | | RSRV |
| 1863 | IMNU | SEATAQ CORP | | | SCAC4 |
| 1864 | IMNZ | INGLEHAND MINERALS & CHEMICALS | | | PWRC |
| 1865 | IMO | Inversiones Moraima, C.A. | Callsign: Invermoca, | YV | AVCODES |
| 1866 | IMO | ImoTrans GmbH | Die Gesellschaft wurde im Jahr 2006 auf PE Cargo verschmolzen | D | TRAFFIC |
| 1867 | IMO | Imotrans | | DE | VKM |
| 1868 | IMOD | INTRAMODAL INC | | | SCAC4 |
| 1869 | IMOE | INTERMODAL EXPRESS INC | | | SCAC4 |
| 1870 | IMOL | IMAR-MOL | | | SCAC4 |
| 1871 | IMOV | INTERNATIONAL MOVING CO | | | SCAC4 |
| 1872 | IMP | Imperial Air | | PE | AVCODES |
| 1873 | IMP | Hellenic Imperial Airways | IATA: HT, Callsign: Imperial, IATA Prefix: 570, Founded in May 2006. Ceased operations in 2012. | GR | AVCODES |
| 1874 | IMPC | IMPACT TRANSPORTATION LLC | | | SCAC4 |
| 1875 | IMPD | IMPEL TRANSPORT LTD | | | SCAC4 |
| 1876 | IMPG | IMPERIAL EAGLE EXPRESS INC | | | SCAC4 |
| 1877 | IMPI | IMPERIAL INTER FREIGHT INC | | | SCAC4 |
| 1878 | IMPK | IMPERIAL - DE GRAVE BV | | | SCAC4 |
| 1879 | IMPN | IMPRITECH INC | | | SCAC4 |
| 1880 | IMPQ | IMP GROUP LIMITED | | | SCAC4 |
| 1881 | IMPR | Imperial | City: Romford | GB | TRAFFIC |
| 1882 | IMPS | IMPERIAL SHIPPING LTD | | | SCAC4 |
| 1883 | IMPU | IMPERIAL CHEMICAL TRANSPORT GMBH | | D | BIC |
| 1884 | IMPY | INTERCARGO LOGISTICS INC | | | SCAC4 |
| 1885 | IMPZ | IMPERIAL INC. | | | PWRC |
| 1886 | IMQT | IMT TRANSPORT | | | SCAC4 |
| 1887 | IMR | Imaer | Callsign: Imaer, | P | AVCODES |
| 1888 | IMR | Imaer | | | ICAO1 |
| 1889 | IMRD | IRON MOUNTAIN RECORDS | | | SCAC4 |
| 1890 | IMRF | INTERNATIONAL MOTOR FREIGHT INC | | | SCAC4 |
| 1891 | IMRG | IMR METALLURGICAL RESOURCES AG | | | SCAC4 |
| 1892 | IMRI | INTERNATIONAL MARINE SALVAGE INC | | | SCAC4 |
| 1893 | IMRK | INTERMARK TRANSPORT INC | | | SCAC4 |
| 1894 | IMRL | Iowa Chicago and Eastern R.R. Corp. | added 10/2002; added 1/2003; 7/2005; eliminated 1/2010 | | NAKINA |
| 1895 | IMRL | I & M Rail Link, LLC | added 7/1997; 7/2000; eliminated 10/2002; eliminated 1/2003 | | NAKINA |
| 1896 | IMRL | I & M Rail Link, LLC | added 7/97; 7/2000 | | NRHS |
| 1897 | IMRL | IOWA, CHICAGO & EASTERN RAILROAD [I & M RAIL LINK LLC; ILLINOIS & MISSOURI RAIL LINK] | | | PWRC |
| 1898 | IMRL | Illinois and Missouri Rail Link (Iowa, Chicago and Eastern Railroad) | | | RSRV |
| 1899 | IMRL | I & M Rail Link, LLC | | USA | TRAFFIC |
| 1900 | IMRN | INTERNATIONAL MARINE TRANSPORT, INC. | | | SCAC1 |
