| Abbreviation | Definition |
|---|---|
| PNHU | Speedie Lube Of Hawaii |
| PNHX | GATX Capital Corporation |
| PNHX | General American Marks (GATX Corporation) |
| PNMD | Train routing Port Huron, Michigan, to Midland, Michigan |
| PNR | Panhandle Northern Railroad |
| PNR | Panhandle Northern Railroad Company |
| PNRW | Piedmont and Northern Railway (Patriot Rail Corporation) |
| PNS | Philadelphia and Norfolk Steamship |
| PNSX | Chem-Nuclear Systems |
| PNSX | Chem-Nuclear Systems L.L.C. |
| PNTX | Great Lakes Chemical Corporation Speciality Chemicals |
| PNTX | Great Lakes Chemical Corporation Specialty Chemicals |
| PNW | Prescott and Northwestern Railroad |
| PNWR | Portland and Western Railroad |
| PNWU | Pacific Northwest Equipment |
| PNWU | Pacific Northwest Equipment Incorporated |
| POAK | Port of Oakland Railway |
| POHC | Pittsburgh and Ohio Central Railroad |
| POLU | Polish Ocean Lines |
| POLU | Polish Ocean Lines Gyndia American Lines |