| 1 | MDR | Compania Mexicana de Aeroplanos, S.A. | Callsign: Aeroplanos, | MEX | AVCODES |
| 2 | MDR | Compania Mexicana De Aeroplanos | | | ICAO1 |
| 3 | MDR | Kansas City Southern Ry. Co. | added 7/1994; 7/2000-7/2005 | | NAKINA |
| 4 | MDR | MidLouisiana Rail Corp. | added 1/1988; 1/1994; eliminated 7/1994 | | NAKINA |
| 5 | MDR | MidLouisiana Rail Corp. | added 1/88; 1/94; eliminated 7/94 | | NRHS |
| 6 | MDR | Kansas City Southern Ry. Co. | added 7/94; 7/2000 | | NRHS |
| 7 | MDR | KANSAS CITY SOUTHERN RAILWAY COMPANY {MIDLOUSIANA RAIL CORP.] | | | PWRC |
| 8 | MDR | Kansas City Southern Railway | | | RSRV |
| 9 | MDRA | M & D RAPIDS TRUCKING | | | SCAC4 |
| 10 | MDRD | MACDOUGALL, ROBERT BRYDEN | | | SCAC4 |
| 11 | MDRF | MEADOW RIDGE FARMS INC | | | SCAC4 |
| 12 | MDRG | MEDINA ROJAS, MARGARITA | | | SCAC4 |
| 13 | MDRI | MDR GLOBAL LOGISTICS LLC | | | SCAC4 |
| 14 | MDRJ | MDR TRANSPORTATION LIMITED | | | SCAC4 |
| 15 | MDRM | MARITIME DREAM SA PANAMA | | | SCAC4 |
| 16 | MDRN | MODERN TRANSFER CO INC | | | PWRC |
| 17 | MDRO | S.E.L. MADURO | | | PWRC |
| 18 | MDRP | M & D TRANSPORT | | | SCAC4 |
| 19 | MDRR | MADORE ENTERPRISES LTD | | | SCAC4 |
| 20 | MDRS | MAQUILADORA AUREA S A DE C V | | | SCAC4 |
| 21 | MDRT | MDR TRANSPORTATION LIMITED | | | SCAC4 |
| 22 | MDRV | MAD RIVER TRANSPORTATION INC | | | SCAC4 |
| 23 | MDRW | MILLER, DOLAN R | | | SCAC4 |
| 24 | MDRX | MDRC-1 LLC | added 10/2003; eliminated 4/2004; 7/2005 (not listed) | | NAKINA |
| 25 | MDRX | Midland Refining Co. (Skelly Oil Co.) | 7/1923 | | NAKINA |
| 26 | MDRX | The Midland Refining Co. | 8/1920 | | NAKINA |
| 27 | MDRX | *SKELLY OIL CO. [MIDLAND REFINING CO.] | | | PWRC |
| 28 | MDRX | +MDRC-1 LLC | | | PWRC |
| 29 | MDRX | MDRC-1 LLC | | | SCAC4 |
| 30 | MDRY | Madison Ry. Co., Inc. | added 1/1978; eliminated 1/1979 | | NAKINA |
| 31 | MDRY | Madison Ry. Co., Inc. | added 1/78; eliminated 1/79 | | NRHS |
| 32 | MDRY | *MADISON RWY. CO. | | | PWRC |
| 33 | MDRY | *RETIRED 08-21-91 ATP (0468) | | | PWRC |
| 34 | MDRY | *MIDLANDS RAILWAY | | | PWRC |
