| 1 | MAT | Maine Aviation Corporation | Callsign: Maine-Av, | USA | AVCODES |
| 2 | MAT | Maine Air Transport, Inc. | Callsign: Maine Air, | USA | AVCODES |
| 3 | MAT | Maine Aviation | | | ICAO1 |
| 4 | MAT | Messer Austria GmbH | | AT | VKM |
| 5 | MATA | Memphis Area Transit Authority | City: Memphis | USA | TRAFFIC |
| 6 | MATB | MATTSON & SON HOUSEMOVING LTD | | | SCAC4 |
| 7 | MATE | MAT EXPRESS (DIVISION OF TRANSNAT E | | | SCAC4 |
| 8 | MATH | MARATHON LOGISTICS | | | SCAC4 |
| 9 | MATI | MATE TRUCKING INC | | | SCAC4 |
| 10 | MATICH | Matsue Ichibata Kotsu | | J | TRAFFIC |
| 11 | MATIS | MATISA Matériel Industriel SA | | CH | VKM |
| 12 | MATIT | Matisa S.p.A | | IT | VKM |
| 13 | MATJ | MERIDIAN AUTO TRANSPORT | | | SCAC4 |
| 14 | MATL | MID-AMERICAN TRUCK LINES INC | | | PWRC |
| 15 | MATL | MARTIN, LANDIS C TRUCKING | | | SCAC4 |
| 16 | MATM | MATMA ENTEPRISES LTD | | | SCAC4 |
| 17 | MATN | MAALT TRANSPORT | | | SCAC4 |
| 18 | MATO | MATEO TRUCKING | | | SCAC4 |
| 19 | MATR | MAYNARD TRANSPORTATION, INC | | | SCAC1 |
| 20 | MATR | Mátra Volán | | H | TRAFFIC |
| 21 | MATS | MATSON NAVIGATION CO. | | | PWRC |
| 22 | MATS | MATSON NAVIGATION CO. | | | SCAC1 |
| 23 | MATS | MATSON NAVIGATION CO | | | SCAC4 |
| 24 | MATS | Matsuura Railway | | J | TRAFFIC |
| 25 | MATSU | Matsumoto Electric Railway | | J | TRAFFIC |
| 26 | MATSUE | Matsue City Transportation Bureau | | J | TRAFFIC |
| 27 | MATT | Mattagami Railroad | | USA | TRAFFIC |
| 28 | MATT | Matthäi Bauunternehmen | | DE | VKM |
| 29 | MATU | MATSON NAVIGATION COMPANY, INC | | USA | BIC |
| 30 | MATU | MATSON NAVIGATION CO. | | | PWRC |
| 31 | MATU | Matson Navigation | | | RSRV |
| 32 | MATU | MATSON NAVIGATION COMPANY INC | | | SCAC4 |
| 33 | MATV | MATS INC | | | SCAC4 |
| 34 | MATX | Railmark | added 1/1989 | | NAKINA |
| 35 | MATX | Merchants Investment Co. | added 4/1975; 1/1980; eliminated 1/1989 | | NAKINA |
| 36 | MATX | Mid-American Car & Equipment Co. | added 7/1965; 7/1965-1/1975; eliminated 4/1975 | | NAKINA |
| 37 | MATX | Mather Collieries | 7/1923-7/1930 | | NAKINA |
| 38 | MATX | Mid-American Car & Equipment Co. | added 7/65; 7/65-1/75; eliminated 4/75 | | NRHS |
| 39 | MATX | Merchants Investment Co. | added 4/75; 1/80; eliminated 1/89 | | NRHS |
| 40 | MATX | Railmark | added 1/89 | | NRHS |
| 41 | MATX | *MATHER COLLERIES | | | PWRC |
| 42 | MATX | *MARYLAND TRANSIT ADMINISTRATION | | | PWRC |
| 43 | MATX | *RAILMARK [MERCHANTS INVESTMENT CO.; MID-AMERICAN CAR & EQUIPMENT CO.] | | | PWRC |
| 44 | MATX | *MARYLAND TRANSIT ADMINISTRATION | | | PWRC |
| 45 | MATX | Merchants Investment | | | RSRV |
| 46 | MATY | MCTYRE TRUCKING COMPANY INC | | | SCAC4 |
| 47 | MATZ | MATSON NAVIGATION CO. | | | PWRC |
| 48 | MATZ | Matson Navigation | | | RSRV |
| 49 | MATZ | MATSON NAVIGATION CO. | | | SCAC4 |
