| 1 | MEP | Midwest Express Airlines, Inc. | IATA: YX, Callsign: Midex, IATA Prefix: 453, Name changed to Midwest Airlines, Inc. w.e.f. 28 February 2003. | USA | AVCODES |
| 2 | MEP | Midwest Airlines, Inc. | IATA: YX, Callsign: Midex, IATA Prefix: 453, Name changed to Republic Airlines, Inc d/b/a Midwest Airlines, Inc. Name changed from Midwest Express Airlines, Inc. w.e.f. 28 February 2003. | USA | AVCODES |
| 3 | MEP | Republic Airlines, Inc d/b/a Midwest Airlines, Inc. | IATA: YX, Callsign: Midex, IATA Prefix: 453, Merged into Frontier Airlines w.e.f. 03 November 2010. Name changed from Midwest Airlines, Inc. w.e.f. 23 June 2009. | USA | AVCODES |
| 4 | MEP | Midwest Airlines | IATA: YX | | ICAO1 |
| 5 | MEPB | METRO PAPER BOX LIMITED | | | SCAC4 |
| 6 | MEPD | MITSUBISHI ELECTRIC POWER PRODUCTS | | | SCAC4 |
| 7 | MEPH | MERCIER, PHILIPPE (1994) INC | | | SCAC4 |
| 8 | MEPI | MCDONALD TRANSPORTATION INC | | | SCAC4 |
| 9 | MEPJ | MSC EXPEDITOR INC | | | SCAC4 |
| 10 | MEPK | MRN ENTERPRISES INC | | | SCAC4 |
| 11 | MEPM | MARCO ENTERPRISES LLC | | | SCAC4 |
| 12 | MEPQ | MERRITT ENERGY PARTNERS | | | SCAC4 |
| 13 | MEPR | MITCHEL ENTERPRISES CORPORATION | | | SCAC4 |
| 14 | MEPS | MEP LOGISTICS | | | SCAC4 |
| 15 | MEPT | M E P TRUCKING | | | SCAC4 |
| 16 | MEPV | MOLDURAS EL PURRUN SA DE CV | | | SCAC4 |
| 17 | MEPW | MARITIME EQUITY PARTNERS LLC | | | SCAC4 |
| 18 | MEPX | McGraw-Edison Co. | added 4/1969; 4/1970-1/1980; eliminated 10/1993; 1/1994-7/2005 (not listed) | | NAKINA |
| 19 | MEPX | McGraw-Edison Co. | added 4/69; 4/70-1/80; eliminated 10/93; 1/94-7/2000 | | NRHS |
| 20 | MEPX | *MEAD PAPER COMPANY | | | PWRC |
| 21 | MEPX | +McGRAW-EDISON COMPANY | | | PWRC |
| 22 | MEPX | McGraw-Edison | | | RSRV |
| 23 | MEPX | MC GRAW-EDISON COMPANY | | | SCAC4 |
