| 2301 | MDW | Midway Airlines | IATA: JI | | ICAO1 |
| 2302 | MDW | Minnesota, Dakota & Western Ry. Co. | 1/1975-7/2005 | | NAKINA |
| 2303 | MDW | Minnesota, Dakota & Western Ry. Co. | 1/75-7/2000 | | NRHS |
| 2304 | MDW | MINNESOTA, DAKOTA & WESTERN RAILWAY CO. | | | PWRC |
| 2305 | MDW | Minnesota, Dakota and Western Railway | | | RSRV |
| 2306 | MDW | MINNESOTA DAKOTA & WESTERN RAILWAY | | | SCAC4 |
| 2307 | MDW | Minnesota, Dakota & Western | | USA | TRAFFIC |
| 2308 | MDWC | MIDWEST CARRIERS INC | | | SCAC4 |
| 2309 | MDWE | MID-WEST MATERIAL WAREHOUSING SERVI | | | SCAC4 |
| 2310 | MDWF | MIDWEST FARMERS COOPERATIVE | | | SCAC4 |
| 2311 | MDWI | MIDWEST TRANSPORT SPECIALISTS INC | | | SCAC4 |
| 2312 | MDWK | MCANDREW TRANSPORTATION | | | SCAC4 |
| 2313 | MDWL | MIDWEST EXPRESS LOGISTICS LLC | | | SCAC4 |
| 2314 | MDWM | MDW EXPRESS TRANSPORT LTD | | | SCAC4 |
| 2315 | MDWN | MIDWESTERN TRANSIT SERVICE INC | | | SCAC4 |
| 2316 | MDWO | MIDWEST COURIER INC | | | SCAC4 |
| 2317 | MDWQ | MD THERMOWINDOWS LTD | | | SCAC4 |
| 2318 | MDWT | MIDWEST TRANSPORTATION RESOURCES LL | | | SCAC4 |
| 2319 | MDWU | MINNESOTA, DAKOTA AND WESTERN RAILWAY CO. | | | PWRC |
| 2320 | MDWU | Minnesota, Dakota and Western Railway | | | RSRV |
| 2321 | MDWV | MIDWEST RAIL AND DISMANTLING INC | | | SCAC4 |
| 2322 | MDWW | MCCUNE DESIGN WOODWORKS | | | SCAC4 |
| 2323 | MDWY | MIDWAY MOTOR FREIGHT LINES, INC | | | SCAC1 |
| 2324 | MDWY | MEADWA | | | SCAC4 |
| 2325 | MDWZ | MINNESOTA, DAKOTA AND WESTERN RAILWAY CO. | | | PWRC |
| 2326 | MDWZ | Minnesota, Dakota and Western Railway | | | RSRV |
| 2327 | MDWZ | MINNESOTA DAKOTA & WESTERN RAILWAY | | | SCAC4 |
| 2328 | MDX | Aerosud Charter | Callsign: Medair, Name changed to Medair Charter (Pty) Ltd | ZA | AVCODES |
| 2329 | MDX | Medair Charter (Pty) Ltd | Callsign: Medair, Name changed from Aerosud Charter. | ZA | AVCODES |
| 2330 | MDX | Aerosud Charter | | | ICAO1 |
| 2331 | MDXB | MERIDIAN EXPRESS INC | | | SCAC4 |
| 2332 | MDXC | MIDWEST DIRECT TRANSPORT INC. | | | SCAC4 |
| 2333 | MDXD | MASON & DIXON LINES (LOGISTICS DIVI | | | SCAC4 |
| 2334 | MDXF | M & D AUTO TRANSPORT LLC | | | SCAC4 |
| 2335 | MDXG | MDX LOGISTICS LLC | | | SCAC4 |
| 2336 | MDXH | M & D TRANSPORT INC | | | SCAC4 |
| 2337 | MDXJ | MDA CONTAINER TRANSPORTATION INC | | | SCAC4 |
| 2338 | MDXK | MDN TRANSPORT | | | SCAC4 |
| 2339 | MDXL | MIDTEX LOGISTICS INC | | | SCAC4 |
| 2340 | MDXO | MALLARD TRANSFER LLC | | | SCAC4 |
| 2341 | MDXP | MIDAS EXPRESS | | | SCAC1 |
| 2342 | MDXP | MODERN EXPRESS INC | | | SCAC4 |
| 2343 | MDXS | M D EXPRESS | | | SCAC4 |
| 2344 | MDXT | MIDTEX TRANSPORTATION INC | | | SCAC4 |
| 2345 | MDXU | MADDOX HOLDING B V | | | SCAC4 |
| 2346 | MDXV | MEDICAL TRANSIT SERVICES | | | SCAC4 |
| 2347 | MDXW | MEDALLION TRANSPORT & LOGISTICS LLC | | | SCAC4 |
| 2348 | MDXY | MID-ATLANTIC TRANSPORT CORPORATION | | | SCAC4 |
| 2349 | MDY | Mediterranean Airways | | ET | AVCODES |
| 2350 | MDY | Mediterranean Airways | | | ICAO1 |
| 2351 | MDYK | MOUDRY TRUCKING | | | SCAC4 |
| 2352 | MDYL | MIKES DELIVERY SERVICE LLC | | | SCAC4 |
| 2353 | MDYN | MAC DADDY TRUCKING INC | | | SCAC4 |
| 2354 | MDYP | MULTIMODAL DRAYAGE SERVICE LLC | | | SCAC4 |
| 2355 | MDYQ | MOTION DYNAMICS RACING INCORPORATED | | | SCAC4 |
| 2356 | MDYR | MAGNOLIA DELIVERY SERVICE | | | SCAC4 |
| 2357 | MDYT | MID-WAY TRANSPORTATION INC | | | SCAC4 |
| 2358 | MDYV | MUSKOK | | | SCAC4 |
| 2359 | MDZ | Mid Airlines | Callsign: Midanes, Designator MT recalled by IATA | ZW | AVCODES |
| 2360 | MDZ | Mid Airlines | IATA: MT, Designator MT recalled by IATA | ZW | AVCODES |
| 2361 | MDZC | M D Z TRUCKING LLC | | | SCAC4 |
| 2362 | MDZF | MARDALE FARMS | | | SCAC4 |
| 2363 | MDZG | MENENDEZ TRUCKING | | | SCAC4 |
| 2364 | MDZJ | MENDEZ, JESUS MORA | | | SCAC4 |
| 2365 | MDZL | MENDOZA LOPEZ, URBANO | | | SCAC4 |
| 2366 | MDZM | MALAGON DIAZ, MONICA | | | SCAC4 |
| 2367 | MDZT | MENDOZA & SONS TRANSPORT LLC | | | SCAC4 |
| 2368 | ME | Morristown & Erie Ry., Inc. | added 1/1988; 1/1994-7/2005; eliminated 1/2008 | | NAKINA |
| 2369 | ME | Morristown & Erie R.R. Co. | 1/1975-1/1980; added 1/1986; eliminated 1/1988 | | NAKINA |
| 2370 | ME | Mississippi Eastern Ry. | 7/1923-7/1954 | | NAKINA |
| 2371 | ME | Mississippi Eastern Ry. | 4/38-1/52 | | NRHS |
| 2372 | ME | Morristown & Erie R.R. Co. | 1/75-1/80; added 1/86; eliminated 1/88 | | NRHS |
| 2373 | ME | Morristown & Erie Ry., Inc. | added 1/88; 1/94-7/2000 | | NRHS |
| 2374 | ME | *MISSISSIPPI EASTERN RWY. | | | PWRC |
| 2375 | ME | +MORRISTOWN & ERIE RAILWAY, INC | | | PWRC |
| 2376 | ME | Morristown and Erie Railway | | | RSRV |
| 2377 | ME | MORRISTOWN & ERIE RAILWAY INC | | | SCAC4 |
| 2378 | ME | Morristown & Erie | | USA | TRAFFIC |
| 2379 | MEA | Middle East Airlines | IATA: ME | | ICAO1 |
| 2380 | MEAA | MEA NURSERY | | | SCAC4 |
| 2381 | MEAB | MALIBU EXPRESS TRUCKING | | | SCAC4 |
| 2382 | MEAC | MENDOZA ACOSTA, URIEL | | | SCAC4 |
| 2383 | MEAD | MEADOWS PETROLEUM PRODUCTS INC | | | SCAC4 |
| 2384 | MEAE | MARROQUIN ELIZONDO, ANDRES RAFAEL | | | SCAC4 |
| 2385 | MEAH | MATH EXPRESS INC | | | SCAC4 |
| 2386 | MEAI | MELBOURNE EAU GALLE MOVING & STORAG | | | SCAC4 |
| 2387 | MEAK | MC EXPRESS TRUCKING LLC | | | SCAC4 |
| 2388 | MEAN | MEANS MOTOR SPORTS LLC | | | SCAC4 |
| 2389 | MEAO | METAL EXCHANGE CORPORATION | | | SCAC4 |
| 2390 | MEAP | MELTON, BOB TRUCK SERVICE INC | | | SCAC4 |
| 2391 | MEAT | MACDONALD MEAT COMPANY | | | SCAC4 |
| 2392 | MEAU | BIANCHI ASIA (SHANGHAI) LTD. | | PRC | BIC |
| 2393 | MEAU | STAR CONTAINER SERVICES GMBH | | | SCAC4 |
| 2394 | MEAW | MESSING, MICHAEL RAYMOND | | | SCAC4 |
| 2395 | MEAY | MEYER SERVICE & SUPPLY LTD | | | SCAC4 |
| 2396 | MEB | MEB -Bahndienstleistungen GmbH | | DE | VKM |
| 2397 | MeBa | MecklenburgBahn GmbH | Schwerin | D | privat-bahn.de |
| 2398 | MEBA | MecklenburgBahn | | D | TRAFFIC |
| 2399 | MEBB | MAPLES TRUCKING INC | | | SCAC4 |
| 2400 | MEBD | MEDINA BLANKING INC | | | SCAC4 |
