| 1 | ATR | Atlas Airlines | Callsign: Atlas-Air, | USA | AVCODES |
| 2 | ATR | Atlas Airlines | | | ICAO1 |
| 3 | ATR | Alliance Terminal Rd., LLC | 7/2005 | | NAKINA |
| 4 | ATR | ALLIANCE TERMINAL RD., LLC | | | PWRC |
| 5 | ATR | Alliance Terminal Railroad | | | RSRV |
| 6 | ATR | ALLIANCE TERMINAL RAILROAD LLC | | | SCAC4 |
| 7 | ATRAM | Autotram Jerzy Grondalski | | PL | TRAFFIC |
| 8 | ATRB | ABRAM, PAUL TRUCKING & ABRAM READY- | | | SCAC3 |
| 9 | ATRB | AUTOTRANSPORTES DE CARGA RUBEN TORR | | | SCAC4 |
| 10 | ATRC | AMER-TRANS RELOCATION SERVICES INC | | | SCAC4 |
| 11 | ATRD | ALLTRANSPORT INC | | | SCAC3 |
| 12 | ATRD | AUTOTRANSPORTES DE CARGA PEGA S A D | | | SCAC4 |
| 13 | ATRE | ABLE TREK TOURS INC | | | SCAC4 |
| 14 | ATRF | ARROWHEAD TRANSFER, INC | | | SCAC3 |
| 15 | ATRF | ARROWHEAD TRANSFER INC | | | SCAC4 |
| 16 | ATRI | ALLEN TRANSFER & STORAGE CO | | | SCAC3 |
| 17 | ATRI | ALCANTAR IBARRA, MARTE GUADALUPE | | | SCAC4 |
| 18 | ATRI | Alpha Trains Iberia | | E | TRAFFIC |
| 19 | ATRJ | ATKINSON, R J | | | SCAC3 |
| 20 | ATRK | A T TRUCKING CO | | | SCAC3 |
| 21 | ATRL | AGRI TRANSPORT | | | SCAC4 |
| 22 | ATRN | ASSOCIATED TRANSPORTATION SYSTEMS I | | | SCAC4 |
| 23 | ATRO | AREA TRANSPORTATION CO | | | SCAC3 |
| 24 | ATRO | ACCENT RELOCATION SERVICES INC | | | SCAC4 |
| 25 | ATROL | Komunalno Društvo Autotrolej doo | City: Rijeka | HR | TRAFFIC |
| 26 | ATRP | AUTO RELOCATION PLUS INC | | | SCAC4 |
| 27 | ATRQ | ACE TRANSFER & WAREHOUSE CO | | | SCAC3 |
| 28 | ATRR | ANDERSON TRUCKING SERVICE | | | SCAC3 |
| 29 | ATRR | AUTOTRANSPORTES RUBELV | | | SCAC4 |
| 30 | ATRR | ATIR RAIL | | FR | VKM |
| 31 | ATRS | AMERICAN TRANSPORTATION OF WISCONSI | | | SCAC3 |
| 32 | ATRS | AMERICAN TRANSPORTATION OF WISCONSI | | | SCAC4 |
| 33 | ATRU | ANELTRANS PIATKIEWICZ SP. K. | | PL | BIC |
| 34 | ATRU | ANTRAK GROUP LTD | | | SCAC3 |
| 35 | ATRU | ANTRAK GROUP LTD | | | SCAC4 |
| 36 | ATRW | Anthracite Ry., Inc. | added 10/1983; eliminated 10/1989 | | NAKINA |
| 37 | ATRW | Anthracite Ry., Inc. | added 10/83; eliminated 10/89 | | NRHS |
| 38 | ATRW | ANTHRACITE RAILWAY | | | PWRC |
| 39 | ATRW | Anthracite Railway | | | RSRV |
| 40 | ATRW | ALLIANCE TRANSPORTATION SERVICES LT | | | SCAC4 |
| 41 | ATRX | A.B.C. Transit Refrigeration Co. | 8/1920 | | NAKINA |
| 42 | ATRX | *A.B.C. TRANSIT REFRIGERATION CO. | | | PWRC |
| 43 | ATRX | *ATLANTA RAILCAR COMPANY | | | PWRC |
| 44 | ATRX | ATLANTA RAILCAR COMPANY | | | SCAC4 |
| 45 | ATRY | ATLANTIC RELOCATION SYSTEMS | | | SCAC4 |
