| 9401 | RTRQ | RATE TRANSPORT CO INC | | | SCAC4 |
| 9402 | RTRR | ROADTRAIN TRAILER REPAIR INC | | | SCAC3 |
| 9403 | RTRR | ROADRUNNER TRANSPORTATION | | | SCAC4 |
| 9404 | RTRT | ROSE TRAILER TOTERS | | | SCAC3 |
| 9405 | RTRU | RÉVÉSZ TRANS KFT. | | H | BIC |
| 9406 | RTRU | ROAD TRAILER RENTALS INCORPORATED | | | PWRC |
| 9407 | RTRU | Road Trailer Rentals | | | RSRV |
| 9408 | RTRV | RAM TOUR & TRAVEL | | | SCAC3 |
| 9409 | RTRV | REEVES TRUCKING | | | SCAC4 |
| 9410 | RTRW | REDDEN TRUCKING | | | SCAC3 |
| 9411 | RTRX | Rocky Mountain Transportation Services | added 7/1995; 7/2000-7/2005 | | NAKINA |
| 9412 | RTRX | E.I. du Pont de Nemours & Co., Inc. | added 7/1963; 7/1965; eliminated 1/1966 | | NAKINA |
| 9413 | RTRX | E.I. du Pont de Nemours & Co., Inc. | added 7/63; 7/65; eliminated 1/66 | | NRHS |
| 9414 | RTRX | Rocky Mountain Transportation Services | added 7/95; 7/2000 | | NRHS |
| 9415 | RTRX | *E. I. DU PONT DE NEMOURS & CO., INC. | | | PWRC |
| 9416 | RTRX | *RAILTOWN 1897 RAILROAD | | | PWRC |
| 9417 | RTRX | +ROCKY MOUNTAIN TRANSPORTATION SERVICES | | | PWRC |
| 9418 | RTRX | Rocky Mountain Transportation Services | | | RSRV |
| 9419 | RTRX | ROCKY MOUNTAIN TRANSPORTATIN SERVIC | | | SCAC4 |
| 9420 | RTRY | RICHARDSON TRUCKING | | | SCAC4 |
| 9421 | RTRZ | ROAD TRAILER RENTALS LIMITED | | | PWRC |
| 9422 | RTRZ | Road Trailer Rentals Limited | | | RSRV |
| 9423 | RTRZ | ROAD TRAILER RENTALS, INC. | | | SCAC4 |
| 9424 | RTS | Relief Transport Services Ltd. | Callsign: Relief, | GB | AVCODES |
| 9425 | RTS | Relief Transport Services | | | ICAO1 |
| 9426 | RTS | Rail Transport Service Germany GmbH | München (Ableger von RTS Austria - Swietelsky) | D | privat-bahn.de |
| 9427 | RTS | RICHARDS TRANSPORTATION SERVICE INC | | | SCAC4 |
| 9428 | RTS | Rail Transport Service GmbH | | A | TRAFFIC |
| 9429 | RTS | RTS Rail Transport Service GmbH | | AT | VKM |
| 9430 | RTSA | RIVERSIDE TRUCK & STORAGE CO | | | SCAC3 |
| 9431 | RTSA | Rail Technical Support | Real: rts | AUS | TRAFFIC |
| 9432 | RTSB | RELIABLE TRANSPORTATION SOLUTIONS L | | | SCAC4 |
| 9433 | RTSC | RILEY TRUCKING SERVICE INC | | | SCAC3 |
| 9434 | RTSC | RTS | | | SCAC4 |
| 9435 | RTSC | RTS Rail Traction Services (Switzerland) AG | Real: RTS | CH | TRAFFIC |
| 9436 | RTSD | R T S TRUCKING LLC | | | SCAC4 |
| 9437 | RTSE | RTS ENTERPRISES | | | SCAC3 |
| 9438 | RTSF | RUTLAND TOOL SERVICE INC | | | SCAC3 |
| 9439 | RTSF | RUSSELLS TREE & SHRUB FARM LLC | | | SCAC4 |
| 9440 | RTSH | RT SYSTEMS INC | | | SCAC3 |
| 9441 | RTSI | ROBINHOOD TOWING SERVICE | | | SCAC3 |
| 9442 | RTSI | ROBINHOOD TOWING SERVICE | | | SCAC4 |
| 9443 | RTSJ | R T S TRANSPORTATION INC | | | SCAC3 |
| 9444 | RTSK | RUST & SONS TRUCKING INC | | | SCAC4 |
| 9445 | RTSL | RICHARDSON TRANSPORT LTD | | | SCAC3 |
| 9446 | RTSM | RTS TRANSPORTATION SYSTEMS INC | | | SCAC3 |
| 9447 | RTSN | RTS INVESTMENT CORPORATION | | | SCAC3 |
| 9448 | RTSN | REAVES TRANSPORTATION SERVICES LLC | | | SCAC4 |
| 9449 | RTSO | RAINS TRUCKING SERVICE INC | | | SCAC3 |
| 9450 | RTSQ | RAPID TRANSFER & STORAGE CO | | | SCAC3 |
| 9451 | RTSQ | RAPID TRANSFER & STORAGE CO | | | SCAC4 |
| 9452 | RTSR | Rail Transportation Services, Inc. | added 7/1996 | | NAKINA |
| 9453 | RTSR | Rail Transportation Services, Inc. | added 7/96 | | NRHS |
| 9454 | RTSR | RAIL TRANSPORTATION SERVICES, INC. | | | PWRC |
| 9455 | RTSR | RICHMOND TRAFFIC SERVICES INC | | | SCAC3 |
| 9456 | RTSRC | Regional Transit Service | in Riverside, California | USA | TRAFFIC |
| 9457 | RTSS | ROADCO TRANSPORTATION SERVICES, INC. | | | SCAC3 |
| 9458 | RTSS | ROADCO TRANSPORTATION SERVICES INC | | | SCAC4 |
| 9459 | RTST | ROOTS TRANSFER INC | | | SCAC3 |
| 9460 | RTSU | ROBERT KUKLA GMBH | | D | BIC |
| 9461 | RTSU | RENT TANK AG | | | SCAC3 |
| 9462 | RTSU | ROBERT KUKLA GMBH | | | SCAC4 |
| 9463 | RTSW | RAM TRANS SYSTEMS INC | | | SCAC3 |
| 9464 | RTSW | R T S | | | SCAC4 |
| 9465 | RTSX | Rail Transportation Services Inc. | 7/2000; eliminated 10/2002; 7/2005 (not listed) | | NAKINA |
| 9466 | RTSX | Rail Transportation Services Inc. | Jul-00 | | NRHS |
| 9467 | RTSX | RAIL TRANSPORTATION SERVICES, INC. | | | PWRC |
| 9468 | RTSX | Rail Transportation Services | | | RSRV |
| 9469 | RTSY | RAM TRANSPORT SYSTEMS INC | | | SCAC3 |
| 9470 | RTSY | RTS MOVING SERVICES | | | SCAC4 |
| 9471 | RTT | Titan Aero Airlines, Closed Joint-Stock Company | Callsign: Rustitan, | RUS | AVCODES |
| 9472 | RTT | RIVER TRAILS TRANSIT LINES INC | | | SCAC4 |
| 9473 | RTT | RAILTRANSPORT s.r.o. | | CZ | VKM |
| 9474 | RTTA | R T TRANSPORTATION INCORPORATED | | | SCAC3 |
| 9475 | RTTC | REFINERS TRANSPORT & TERMINAL CORPO | | | SCAC3 |
| 9476 | RTTD | R T TRANSPORT INC | | | SCAC3 |
| 9477 | RTTE | RT&T ENTERPRISES INC | | | SCAC4 |
| 9478 | RTTF | R & T TRANSPORT | | | SCAC3 |
| 9479 | RTTH | RITTER TRUCKING | | | SCAC3 |
| 9480 | RTTI | ROTTIER TRUCKING INC | | | SCAC3 |
| 9481 | RTTJ | RTTJ TRANSPORTATION INC | | | SCAC3 |
| 9482 | RTTK | R T TRUCKING INC | | | SCAC4 |
| 9483 | RTTL | REUTER, TODD TRUCKING LLC | | | SCAC4 |
| 9484 | RTTM | RYAN, TIM TRUCKING LLC | | | SCAC4 |
| 9485 | RTTN | R T TRANSPORTATION | | | SCAC4 |
| 9486 | RTTP | RITTER TRANSPORTATION | | | SCAC3 |
| 9487 | RTTP | Rīgas Tramvaju un Trolejbusu Pārvalde | City: Riga | LV | TRAFFIC |
| 9488 | RTTR | RTR TRANSPORTATION SERVICES | | | SCAC4 |
| 9489 | RTTS | R T T S INC | | | SCAC4 |
| 9490 | RTTT | RITTER TRUCKING | | | SCAC3 |
| 9491 | RTTU | RASA TECHNOLOGY TAIWAN LTD | | RC | BIC |
| 9492 | RTTU | RASA TECHNOLOGY TAIWAN LTD | | | SCAC4 |
| 9493 | RTTV | ROYS TOW & TRANSPORT SERV | | | SCAC3 |
| 9494 | RTTX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 9495 | RTTX | Trailer Train Co. | added 1/1961; 4/1961-1/1980; eliminated 7/1984; added 7/1986; eliminated 1/1992 | | NAKINA |
| 9496 | RTTX | Rapid Transit Tank Car Line | 7/1923 | | NAKINA |
| 9497 | RTTX | Trailer Train Co. (not defined) | added 1/1961; 4/1961 | | NAKINA |
| 9498 | RTTX | Trailer Train Co. (FCS flat cars equipped with tri-level automobile carrying superstructures furnished by member railroads. Cars are not equipped with hitches and bridge plates) | 4/1963 | | NAKINA |
| 9499 | RTTX | Trailer Train Co. (FA flat cars equipped with tri-level automobile carrying superstructures furnished by member railroads. Cars are not equipped with hitches and bridge plates) | 7/1965-10/1968 | | NAKINA |
| 9500 | RTTX | Trailer Train Co. (flat cars, equipped with fixed tri-level auto racks furnished by participant railroads) | 4/1970-1/1980 | | NAKINA |
