| Abbreviation | Definition |
|---|---|
| GPEX | General American Transportation Corporation (GATX Corporation) |
| GPFX | GATX Corporation |
| GPFX | General American Marks Company |
| GPIX | General Portland (Sunbelt Cement) |
| GPIX | Sunbelt Cement |
| GPLU | Management Control and Maintenance |
| GPLU | Management Control and Maintenance, S. A. |
| GPLX | General American Marks (GATX Corporation) |
| GPLX | General American Marks Company |
| GPMX | Georgia-Pacific Corporation - Mid Continent Wood Products Manufacturing Division |
| GPMX | Georgia-Pacific Corporation (Mid Continent Wood Products Manufacturing Division) |
| GPPX | Georgia-Pacific Corporation (Portland Division) |
| GPPX | Georgia-Pacific Corporation Chemical Division |
| GPRT | Gippsland Plains Rail Trail |
| GPSX | Georgia-Pacific Corporation (Eastern Wood Products Manufacturing Division) |
| GPSX | Georgia-Pacific Corporation Eastern Wood Products Manufacturing Division |
| GPUX | GPU Service Corporation |
| GR | Grand Rapids Eastern Railroad |
| GR | Grand Rapids Eastern Railroad Incorporated |
| GRCX | Granite Rock |