| Abbreviation | Definition |
|---|---|
| HFPX | General American Transportation Corporation (GATX) |
| HFY | Harpers Ferry Station (MARC Rail- AMTK) |
| HGAU | Hybas International |
| HGBR | Hamilton, Grimsby, and Beamsville Electric Railway |
| HGCX | Hillsboro Glass |
| HGIU | Hub Group, Incorporated |
| HGIZ | Hub Group, Incorporated |
| HGPX | Harrison Gypsum |
| HGPX | Harrison Gypsum Company |
| HHCX | Huntsman |
| HHEX | H and H Engineering Construction |
| HHHX | Public Service of Colorado |
| HHL | Haverhill Station (MBTA T Commuter Rail - AMTK) |
| HHLX | H and H Locomotive Leasing |
| HI | Holton Interurban Railway |
| HIIX | Hamburg Industries (TTX) |
| HIIX | TTX Company - Hamburg Division |
| HIMX | Heppner Iron and Metal |
| HINX | Heritage Inks International Corporation |
| HIPX | Houston Industries Incorporated - Houston Lighting and Power Company |