| 1 | ME | Morristown & Erie Ry., Inc. | added 1/1988; 1/1994-7/2005; eliminated 1/2008 | | NAKINA |
| 2 | ME | Morristown & Erie R.R. Co. | 1/1975-1/1980; added 1/1986; eliminated 1/1988 | | NAKINA |
| 3 | ME | Mississippi Eastern Ry. | 7/1923-7/1954 | | NAKINA |
| 4 | ME | Mississippi Eastern Ry. | 4/38-1/52 | | NRHS |
| 5 | ME | Morristown & Erie R.R. Co. | 1/75-1/80; added 1/86; eliminated 1/88 | | NRHS |
| 6 | ME | Morristown & Erie Ry., Inc. | added 1/88; 1/94-7/2000 | | NRHS |
| 7 | ME | *MISSISSIPPI EASTERN RWY. | | | PWRC |
| 8 | ME | +MORRISTOWN & ERIE RAILWAY, INC | | | PWRC |
| 9 | ME | Morristown and Erie Railway | | | RSRV |
| 10 | ME | MORRISTOWN & ERIE RAILWAY INC | | | SCAC4 |
| 11 | ME | Morristown & Erie | | USA | TRAFFIC |
| 12 | MEA | Middle East Airlines | IATA: ME | | ICAO1 |
| 13 | MEAA | MEA NURSERY | | | SCAC4 |
| 14 | MEAB | MALIBU EXPRESS TRUCKING | | | SCAC4 |
| 15 | MEAC | MENDOZA ACOSTA, URIEL | | | SCAC4 |
| 16 | MEAD | MEADOWS PETROLEUM PRODUCTS INC | | | SCAC4 |
| 17 | MEAE | MARROQUIN ELIZONDO, ANDRES RAFAEL | | | SCAC4 |
| 18 | MEAH | MATH EXPRESS INC | | | SCAC4 |
| 19 | MEAI | MELBOURNE EAU GALLE MOVING & STORAG | | | SCAC4 |
| 20 | MEAK | MC EXPRESS TRUCKING LLC | | | SCAC4 |
| 21 | MEAN | MEANS MOTOR SPORTS LLC | | | SCAC4 |
| 22 | MEAO | METAL EXCHANGE CORPORATION | | | SCAC4 |
| 23 | MEAP | MELTON, BOB TRUCK SERVICE INC | | | SCAC4 |
| 24 | MEAT | MACDONALD MEAT COMPANY | | | SCAC4 |
| 25 | MEAU | BIANCHI ASIA (SHANGHAI) LTD. | | PRC | BIC |
| 26 | MEAU | STAR CONTAINER SERVICES GMBH | | | SCAC4 |
| 27 | MEAW | MESSING, MICHAEL RAYMOND | | | SCAC4 |
| 28 | MEAY | MEYER SERVICE & SUPPLY LTD | | | SCAC4 |
| 29 | MEB | MEB -Bahndienstleistungen GmbH | | DE | VKM |
| 30 | MeBa | MecklenburgBahn GmbH | Schwerin | D | privat-bahn.de |
| 31 | MEBA | MecklenburgBahn | | D | TRAFFIC |
| 32 | MEBB | MAPLES TRUCKING INC | | | SCAC4 |
| 33 | MEBD | MEDINA BLANKING INC | | | SCAC4 |
| 34 | MEBF | MORALES EXPRESS INC | | | SCAC4 |
| 35 | MEBG | MAINE METAL RECYCLING INC | | | SCAC4 |
| 36 | MEBH | MINER ENTERPRISES LLC | | | SCAC4 |
| 37 | MEBI | MCCARDLES EXPRESS INC | | | SCAC4 |
| 38 | MEBJ | MOUNTAINEER EXPEDITE LLC | | | SCAC4 |
| 39 | MEBK | MEGA EXPRESS INC | | | SCAC4 |
| 40 | MEBM | ME & BROTHERS | | | SCAC4 |
| 41 | MEBMD | MEB-BAHNDIENSTLEISTUNGEN Gmbh | | DE | VKM |
| 42 | MEBQ | MEI TRUCKING LLC | | | SCAC4 |
| 43 | MEBR | MEIBORG BROS INC | | | SCAC4 |
| 44 | MEBT | MELTON, BILL TRUCKING INC | | | SCAC4 |
| 45 | MEBU | MEEBERG CONTAINER SERVICE BV | | NL | BIC |
| 46 | MEBU | MEEBERG CONTAINER SERVICE BV | | | SCAC4 |
| 47 | MEBV | MONVAS ENTERPRISE LTD | | | SCAC4 |
| 48 | MEBW | MIDWAY EXPRESS LTD | | | SCAC4 |
| 49 | MEBY | MARITIME ENERGY | | | SCAC4 |
| 50 | MEC | Mercury Air Cargo, Inc. | IATA: BX, Callsign: Mercair, IATA designator changed to 4X | USA | AVCODES |
| 51 | MEC | Mercury Air Cargo, Inc. d/b/a Air Mercury | IATA: 4X, Callsign: Mercair, IATA Prefix: 805, IATA designator changed from BX* | USA | AVCODES |
| 52 | MEC | Mercury Aircourier Service | | | ICAO1 |
| 53 | MEC | Maine Central R.R. Co. | 7/1930-1/1994; eliminated 4/1997; added 7/1998; 7/2000-7/2005; eliminated 10/2006; added 4/2009 | | NAKINA |
| 54 | MEC | Maine Central R.R. Co. | 4/38-1/94; eliminated 4/97; added 7/98; 7/2000 | | NRHS |
| 55 | MEC | *ST RAIL SYSTEM | | | PWRC |
| 56 | MEC | +GUILFORD RAIL SYSTEM [MAINE CENTRAL RAILROAD] | | | PWRC |
| 57 | MEC | Maine Central Railroad (Pan Am Railways) | | | RSRV |
| 58 | MEC | Maine Central Railroad | | USA | TRAFFIC |
| 59 | MECA | MECCA & SON TRUCKING CORPORATION | | | SCAC1 |
| 60 | MECA | MECCA & SON TRUCKING CORP | | | SCAC4 |
| 61 | MECB | MAPLE CREEK BELGIANS | | | SCAC4 |
| 62 | MECC | Angelo Meccoli | | F | TRAFFIC |
| 63 | MECD | MISCO OF TERRE HAUTE INC | | | SCAC4 |
| 64 | MECDV | MECANO SERV SRL | | RO | VKM |
| 65 | MECG | MTT OF LACROSSE INC | | | SCAC4 |
| 66 | MECHA | MONTAJES ELÉCTRICOS CHAMORRO, S.A. | | ES | VKM |
| 67 | MECI | MARINE EXPLORATION CO INC | | | PWRC |
| 68 | MECJ | MIRANCY EXPRESS INC | | | SCAC4 |
| 69 | MECL | Museums Eisenbahn Club Losheim e.V. | Losheim | D | privat-bahn.de |
| 70 | MECL | MERCANA ART DECOR | | | SCAC4 |
| 71 | MECP | M E C EXPRESS LIMITED | | | SCAC4 |
| 72 | MECQ | MADSEN, SUSAN M | | | SCAC4 |
| 73 | MECS | Mecseki kisvasút - Pécs | | H | TRAFFIC |
| 74 | MECT | MORTENSON CONSTRUCTION | | | SCAC4 |
| 75 | MECU | MELFI MARINE CORP MAIN OFFICE | | | SCAC4 |
| 76 | MECX | Trinity Rail Management, Inc. | added 7/1997; 7/2000-7/2005; eliminated 1/2007 | | NAKINA |
| 77 | MECX | Transcisco Leasing Co. | added 7/1994; eliminated 7/1997 | | NAKINA |
| 78 | MECX | Miner-Edgar Chemical Corp. | 7/1930-7/1932 | | NAKINA |
| 79 | MECX | Miner-Edgar Co. | 8/1920-7/1923 | | NAKINA |
| 80 | MECX | Transcisco Leasing Co. | added 7/94; eliminated 7/97 | | NRHS |
| 81 | MECX | Trinity Rail Management, Inc. | added 7/97; 7/2000 | | NRHS |
| 82 | MECX | *MINER-EDGAR CHEMICAL CORP. | | | PWRC |
| 83 | MECX | *TRINITY RAIL MANAGEMENT INCORPORATED [TRANSCISCO LEASING COMPANY } | | | PWRC |
| 84 | MECX | Trinity Rail Management (Murray Energy Corp) | | | RSRV |
| 85 | MECY | MERCURY TRANSPORTATION INC | | | SCAC4 |
| 86 | MECZ | MILESTONE EQUIPMENT CORPORATION | | | SCAC4 |
| 87 | MED | Ontario Ministry Of Health | Callsign: Medical, | CDN | AVCODES |
| 88 | MED | Med Airways | IATA: 7Y, Founded in 2000 as Flying Carpet. IATA Designator 7Y* recalled | RL | AVCODES |
| 89 | MED | Med Airways | Founded in 2000 as Flying Carpet. IATA Designator 7Y* recalled | RL | AVCODES |
| 90 | MED | Ontario Ministry of Health | | | ICAO1 |
| 91 | MED | MEADOWLAND | | | SCAC4 |
| 92 | MEDA | MEDITERRANEAN AGENCIES | | | PWRC |
| 93 | MEDA | MEDTRANS LLC | | | SCAC4 |
| 94 | MEDD | MED STAR SRL | | | SCAC4 |
| 95 | MEDE | MEDFORD FUEL | | | SCAC4 |
| 96 | MEDF | MAN, E D & F SUGAR INC | | | SCAC4 |
| 97 | MEDG | MEDINA GONZALEZ, JUAN | | | SCAC4 |
| 98 | MEDI | SC Meditur SA | | RO | TRAFFIC |
| 99 | MEDJ | MEDINA GARCIA, JOSE OSCAR | | | SCAC4 |
| 100 | MEDM | MEDINA TRANSPORTATION SERVICES INC | | | SCAC4 |
