| 1 | STT | Air St. Thomas | IATA: ZP, Callsign: Paradise, Designator ZP recalled by IATA. ceased operations in December 2005 | VI | AVCODES |
| 2 | STT | Alpha Star Aviation Services | Callsign: Star Charter, | SA | AVCODES |
| 3 | STT | Western Aircraft, Inc. | IATA: ST, Callsign: Sawtooth, | USA | AVCODES |
| 4 | STT | Air St. Thomas | | | ICAO1 |
| 5 | STT | Svensk Tågteknik AB | 200x - 2009 | S | svenska-lok.se |
| 6 | STT | Svensk Tågteknik AB | | S | TRAFFIC |
| 7 | STT | Svensk Tågteknik AB | | SE | VKM |
| 8 | STTB | STOLT TANK CONTAINERS BV | | | SCAC4 |
| 9 | STTC | STANDARD TRUCKING CO | | | PWRC |
| 10 | STTG | STORM TRUCKING COMPANY/STC LLC | | | SCAC4 |
| 11 | STTI | S & T TRUCKING INC | | | SCAC4 |
| 12 | STTJ | STROH TRANSPORTATION COMPANY | | | SCAC1 |
| 13 | STTK | STAR TRACK LLC | | | SCAC4 |
| 14 | STTL | SUPER TRANSPORTES LOZANO S A DE C V | | | SCAC4 |
| 15 | STTM | STRATMAN TRUCK SERVICE, INC | | | SCAC1 |
| 16 | STTM | STRATMAN TRUCK SERVICE INC | | | SCAC4 |
| 17 | STTP | STEEL TRANSPORTATION SERVICES INC | | | SCAC4 |
| 18 | STTQ | SELLARS TRUCKING | | | SCAC4 |
| 19 | STTR | STAR TRANSPORT | | | SCAC4 |
| 20 | STTR | Stansted Transit | | GB | TRAFFIC |
| 21 | STTRA | Statnett Transport AS | | NO | VKM |
| 22 | STTT | ST TRANSPORT INC | | | SCAC4 |
| 23 | STTU | SHIRLSTAR CONTAINER TRANSPORT LTD | | | PWRC |
| 24 | STTU | Shirlstar Container Transport Limited | | | RSRV |
| 25 | STTX | The Steel and Tube Co. of America | 8/1920-7/1923 | | NAKINA |
| 26 | STTX | Trailer Train Co. | added 10/1958; 4/1961-10/1968; eliminated 4/1970; 1/1975; added 7/1979; 1/1980; eliminated 1/1992 | | NAKINA |
| 27 | STTX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 28 | STTX | Trailer Train Co. (not defined) | added 10/1958; 4/1961 | | NAKINA |
| 29 | STTX | Trailer Train Co. (FC flat cars equipped with hitches, bridge plates and safety chains. Cars are leased to shipper under Plan IV schedule and are free of any mileage charge (Rule 18) to handling roads, but mileage must be reported by car number) | 4/1963 | | NAKINA |
| 30 | STTX | Trailer Train Co. (FC flat cars equipped with hitches, bridge plates and safety chains. Cars are leased to shipper under Plan IV schedule and are free of any mileage charge to handling roads, but mileage must be reported by car number) | 7/1965 | | NAKINA |
| 31 | STTX | Trailer Train Co. (FC flat cars equipped with hitches and bridge plates. Cars are leased to shipper under Plan IV schedule and are free of any mileage charge to handling roads, but mileage must be reported by car number) | 10/1966-10/1968; eliminated 4/1970 | | NAKINA |
| 32 | STTX | Trailer Train Co. (no definition) | 1/1975 | | NAKINA |
| 33 | STTX | Trailer Train Co. | added 7/1979 | | NAKINA |
| 34 | STTX | Trailer Train Co. (flat cars with fixed hitches and no bridge plates for assigned intermodal service between lift-on/lift-off terminals only) | 1/1980 | | NAKINA |
| 35 | STTX | Trailer Train Co./TTX Co. (standard deck flat cars, equipped with collapsable hitches and sliding bridgeplates, capable of handling two 45' dry trailers with 36"" kingpin spacing at either lift-on/lift-off or end loading facilities) | 7/1985-7/2000 | | NAKINA |
| 36 | STTX | Trailer Train Co. | added 10/58; 4/61-7/65 | | NRHS |
| 37 | STTX | Trailer Train Co. (FC flat cars equipped with hitches and bridge plates. Cars are leased to shipper under Plan IV schedule and are free of any mileage charge to handling roads, but mileage must be reported by car number) | 10/66-10/68; eliminated 4/70 | | NRHS |
| 38 | STTX | Trailer Train Co. | Apr-70 | | NRHS |
| 39 | STTX | Trailer Train Co. (no definition) | Jan-75 | | NRHS |
| 40 | STTX | Trailer Train Co. | added 7/79 | | NRHS |
| 41 | STTX | Trailer Train Co. (flat cars with fixed hitches and no bridge plates for assigned intermodal service between lift-on/lift-off terminals only) | Jan-80 | | NRHS |
| 42 | STTX | Trailer Train Co. | eliminated 1/92 | | NRHS |
| 43 | STTX | TTX Co. | added 1/92 | | NRHS |
| 44 | STTX | TTX Co. (standard deck flat cars, equipped with collapsable hitches and sliding bridgeplates, capable of handling two 45' dry trailers with 36" kingpin spacing at either lift on/lift off or end loading facilities) | 1/94-7/2000 | | NRHS |
| 45 | STTX | *STEEL & TUBE CO. OF AMERICA | | | PWRC |
| 46 | STTX | +TTX COMPANY | | | PWRC |
| 47 | STTX | Trailer Train (TTX Corporation) | | | RSRV |
| 48 | STTX | TTX COMPANY | | | SCAC4 |
| 49 | STTZ | STEVENS TRANSPORT | | | PWRC |
| 50 | STTZ | Stevens Transport | | | RSRV |
| 51 | STTZ | STEVENS TRANSPORT | | | SCAC4 |
