| 1 | PRT | Atlantic Coast Jet, Inc. | IATA: DD, Callsign: Patriot, IATA Prefix: 949, IATA designator changed to DD | USA | AVCODES |
| 2 | PRT | Prompt Air, Inc. | Callsign: Prompt Air, | USA | AVCODES |
| 3 | PRT | Atlantic Coast Jet, Inc. | IATA: DD, Callsign: Patriot, IATA Prefix: 949, Desigantor DD recalled by IATA. IATA designator changed from DD* | USA | AVCODES |
| 4 | PRT | Prime Service Italia S.r.l. | Callsign: Prime Italia, | I | AVCODES |
| 5 | PRT | Atlantic Coast Jet | | | ICAO1 |
| 6 | PRT | Parr Terminal R.R. | 1/1975-1/1994; eliminated 7/1997; 7/2000 | | NAKINA |
| 7 | PRT | Parr Terminal R.R. | 1/75-1/94; eliminated 7/97; 7/2000 | | NRHS |
| 8 | PRT | PARR TERMINAL RAILROAD | | | PWRC |
| 9 | PRT | Philadelphia Rapid Transit | | US-PA | TRAFFIC |
| 10 | PRT | Przedsiębiorstwo Robót Torowych “TORREMS” sp. z o. o. | | PL | VKM |
| 11 | PRTA | PRO-TRUCKER | | | SCAC1 |
| 12 | PRTA | PROPANE RESOURCES TRANSPORTATION IN | | | SCAC4 |
| 13 | PRTC | PROVANCE TRUCKING CO | | | SCAC3 |
| 14 | PRTD | Portland Traction Co. | added 10/1989; eliminated 7/1992; 1/1994-7/2005 | | NAKINA |
| 15 | PRTD | Portland Traction Co., Portland R.R. and Terminal Division | 10/1957-1/1980; eliminated 10/1989 | | NAKINA |
| 16 | PRTD | Portland Traction Co., Portland R.R. and Terminal Division | 10/57-1/80; eliminated 10/89 | | NRHS |
| 17 | PRTD | Portland Traction Co. | added 10/89; eliminated 7/92; 1/94-7/2000 | | NRHS |
| 18 | PRTD | PORTLAND TRACTION COMPANY | | | PWRC |
| 19 | PRTD | Portland Traction | | | RSRV |
| 20 | PRTD | PORTLAND TRACTION COMPANY | | | SCAC3 |
| 21 | PRTE | PROTEIN EXPRESS | | | SCAC3 |
| 22 | PRTF | PRUITT, TY TRUCKING | | | SCAC3 |
| 23 | PRTG | PORT TRUCKING INC | | | SCAC4 |
| 24 | PRTH | PROTRANS INC | | | SCAC4 |
| 25 | PRTJ | PRIDE TRANSPORT CO | | | SCAC3 |
| 26 | PRTJ | PETERS TRUCKING INC | | | SCAC4 |
| 27 | PRTK | PRIMA TRUCKING CO | | | SCAC3 |
| 28 | PRTL | PORTILLO BROKERAGE | | | SCAC3 |
| 29 | PRTL | PIELEMEIER TRANSPORT LLC | | | SCAC4 |
| 30 | PRTM | PARTS MOTOR LINES INC | | | SCAC3 |
| 31 | PRTM | PROCTOR TRUCKING | | | SCAC4 |
| 32 | PRTO | PEOPLES, WILLIAM R | | | SCAC3 |
| 33 | PRTO | PARROT TRANSPORT | | | SCAC4 |
| 34 | PRTQ | PRINGLE TRANSFER | | | SCAC3 |
| 35 | PRTR | PORTER, FRANK M, AND FRANCIS PORTER | | | SCAC3 |
| 36 | PRTR | PREMIUM TRANS | | | SCAC4 |
| 37 | PRTS | PROGRESSIVE TRANSPORTATION SERVICES | | | SCAC3 |
| 38 | PRTT | PRATTS TRANSPORTATION, INCORPORATED | | | SCAC3 |
| 39 | PRTU | GS LINES - TRANSPORTES MARITIMOS LDA | | P | BIC |
| 40 | PRTU | PORTLINE-TRANSPORTES MARITIMOS INTE | | | SCAC4 |
| 41 | PRTV | PRINCE TRUCKING INC | | | SCAC3 |
| 42 | PRTX | *PORT RAILROAD | | | PWRC |
| 43 | PRTX | +PEORIA RIVER TERMINAL, INC. | | | PWRC |
| 44 | PRTX | PEORIA RIVER TERMINIAL INC | | | SCAC4 |
| 45 | PRTY | PROUTY TRUCKING INC | | | SCAC3 |
| 46 | PRTZ | PACKER RIVER TERMINAL | | | PWRC |
