| 1 | POR | Porteadora de Cosola S.A. de C.V. | Callsign: Porteadora, | MEX | AVCODES |
| 2 | POR | Porteadora De Cosola | | | ICAO1 |
| 3 | POR | Poseyville and Owensville R.R. Co., Inc. | added 1/1988; eliminated 4/1992; 1/1994 | | NAKINA |
| 4 | POR | Poseyville and Owensville R.R. Co., Inc. | added 1/88; eliminated 4/92; 1/94 | | NRHS |
| 5 | POR | *RETIRED 04-12-93 ATP (339) | | | PWRC |
| 6 | POR | *POSEYVILLE & OWENSVILLE RAILROAD CO. | | | PWRC |
| 7 | PORA | PORT AUTHORITY TRANSIT CORP OF PA & | | | SCAC3 |
| 8 | PORC | PORCO ENERGY CORP | | | SCAC4 |
| 9 | PORE | PORT SERVICE INC | | | SCAC4 |
| 10 | PORF | PORTER TRANSFER CO INC | | | SCAC3 |
| 11 | PORF | PORTER TRANSFER CO INC | | | SCAC4 |
| 12 | PORG | POTTS, RON SR TRUCKING | | | SCAC3 |
| 13 | PORG | POIRIER RACING INC | | | SCAC4 |
| 14 | PORH | PORTER, RALPH | | | SCAC3 |
| 15 | PORH | PRO'S RANCH MARKET INC | | | SCAC4 |
| 16 | PORHA | Pohjois-Suomen Rautatieharrastajat ry | | FI | VKM |
| 17 | PORI | PORTAGE GLACIER CHEVRON | | | SCAC3 |
| 18 | PORK | PORK CHOP TRANSPORT | | | SCAC4 |
| 19 | PORL | PORTER, LYNN | | | SCAC3 |
| 20 | PORM | PORT MOTOR LINES INC | | | SCAC3 |
| 21 | PORO | PORTER, MRS SAM L | | | SCAC3 |
| 22 | PORO | PORTER, DENNIS TRUCKING LTD | | | SCAC4 |
| 23 | PORO | Pórobeton Trutnov, a.s. | | CZ | VKM |
| 24 | PORP | PORTAGE TRANSFER CO, THE | | | SCAC3 |
| 25 | PORQ | PORT CLAREMONT TERMINAL CORP | | | SCAC3 |
| 26 | PORR | PORT NORRIS EXPRESS CO, INC | | | SCAC3 |
| 27 | PORS | PRO TRANSPORT | | | SCAC4 |
| 28 | PORSK | PORFIX - pórobetón, a.s. | | SK | VKM |
| 29 | PORT | PORTAGE TRANSPORT INC | | | SCAC4 |
| 30 | PORT | Interport Service s.r.o. | | SK | VKM |
| 31 | PORTO | Sociedade de Transportes Colectivos do Porto, E.I.M. | Real: STCP, City: Porto | P | TRAFFIC |
| 32 | PORX | Pittsburg Oil & Refining Co. | 7/1923 | | NAKINA |
| 33 | PORX | Pittsburg Oil Refining Co. | 8/1920 | | NAKINA |
| 34 | PORX | *PITTSBURG OIL & REFINING CO. | | | PWRC |
| 35 | PORX | +URANIUM DISPOSITION SERVICES, LLC | | | PWRC |
| 36 | PORX | URANIUM DISPOSITION SERVICES LLC | | | SCAC4 |
| 37 | PORY | PAULSBORO REFINING COMPANY | | | SCAC4 |
