| 1 | MCI | Maya Carga Internacional, S.A. de C.V. | Callsign: Mayacarga, | MEX | AVCODES |
| 2 | MCI | Morocco Airways | Callsign: Morocco-Airways, | MA | AVCODES |
| 3 | MCI | MCI | | USA | TRAFFIC |
| 4 | MCIC | MAX CARGO INC | | | SCAC4 |
| 5 | MCIE | MCINNIS ANTIQUES | | | SCAC4 |
| 6 | MCIF | M C INTL TRANSPORTATION INC | | | SCAC4 |
| 7 | MCIH | MCMICHAEL, R TRUCKING | | | SCAC4 |
| 8 | MCIJ | MCI EXPRESS | | | SCAC4 |
| 9 | MCIL | MALCOLM INTERNATIONAL | | | SCAC4 |
| 10 | MCIN | MACHINERY SERVICES CORPORATION | | | SCAC4 |
| 11 | MCIO | MACIOCIA, MARIO & FILS | | | SCAC4 |
| 12 | MCIP | MCINTOSH, JAMES C | | | SCAC4 |
| 13 | MCIS | MACINTYRE SERVICES LLC | | | SCAC4 |
| 14 | MCIU | MAERSK CONTAINER INDUSTRY AS | | DK | BIC |
| 15 | MCIU | MAERSK CONTAINER INDUSTRY AS | | | SCAC4 |
| 16 | MCIV | MCLANE LIVESTOCK TRANSPORT INC | | | SCAC4 |
| 17 | MCIX | SSI Mobley Co., Inc. (MofW cars) | 1/1994-7/2000 (not listed) | | NAKINA |
| 18 | MCIX | SSI Mobley Co., Inc. | added 4/1989; eliminated 10/1989 | | NAKINA |
| 19 | MCIX | Applied Chemicals Division, Mobley Co., Inc. | 1/1980 | | NAKINA |
| 20 | MCIX | Mooney Chemicals, Inc. | added 1/1959; 4/1961; 7/1965 (not listed) | | NAKINA |
| 21 | MCIX | Monteros & Co., Inc. | 7/1930 | | NAKINA |
| 22 | MCIX | Mooney Chemicals, Inc. | added 1/59; 4/61-7/65 | | NRHS |
| 23 | MCIX | Applied Chemicals Division, Mobley Co., Inc. | Jan-80 | | NRHS |
| 24 | MCIX | SSI Mobley Co., Inc. | added 4/89; eliminated 10/89 | | NRHS |
| 25 | MCIX | SSI Mobley Co., Inc. (MofW cars) | 1/94-7/2000 | | NRHS |
| 26 | MCIX | *MONTEROS & CO., INC. | | | PWRC |
| 27 | MCIX | *MOONEY CHEMICALS, INC. | | | PWRC |
| 28 | MCIX | *SSI MOBLEY COMPANY, INC. (MOW CARS0 [MOBLEY COMPANY, INC., APPLIED CHEMICALS DIV.] | | | PWRC |
| 29 | MCIX | Mobley Applied Chemicals Division | | | RSRV |
| 30 | MCIZ | MIDWEST CARBIDE INC. | | | PWRC |
