| Abbreviation | Definition |
|---|---|
| HPIX | HIMONT USA (Besell USA) |
| HPIX | Montell USA Incorporated |
| HPJX | Helm-Pacific Leasing |
| HPLX | Exxon Company U S A |
| HPLX | Humble Pipe Line (Exxon-Mobil Corporation) |
| HPPX | Huntsman Polypropylene Corporation |
| HPTD | High Point Thomasville and Denton Railroad |
| HPTD | High Point, Thomasville and Denton Railroad |
| HPTU | Highway Pipeline |
| HRB | Heavy Rail Beam |
| HRCX | Heritage Railcar |
| HRD | Helical Rail Design |
| HRDL | Hudson River Day Line |
| HRDX | Hagaman Refining (Silver Star Enterprises) |
| HRDX | Silver Star Enterprises Incorporated |
| HREX | Heavy Railroad Excavations |
| HREX | Heavy Railroad Excavations Incorporated |
| HRLU | Hudson Railway Equipment (Division of Hudson Leasing) |
| HRLU | Hudson Railway Equipment Company |
| HRLZ | Hudson Railway Equipment |