| Abbreviation | Definition |
|---|---|
| DOEX | Doe Run Resources Corporation |
| DOGU | Big Dog Containers |
| DOLX | Dolese Bros. Company |
| DOLX | Dolese Brothers |
| DONX | Donnelly Commodities |
| DOTX | U.S. Department of Transport - Federal Railroad Administration |
| DOTX | United States Department of Transportation (Federal Railroad Administration) |
| DOW | Downingtown Station (SEPTA Regional Rail - AMTK) |
| DOWU | Dow Chemical |
| DOWU | Dow Chemical Company (former Union Carbide rolling stock) |
| DOWX | Dow Chemical |
| DOWX | Dow Chemical Company |
| DP | Diesel Pusher |
| DPCU | Dupont |
| DPCX | Dewey Portland Cement (Dragon Products) |
| DPDZ | Delaware and Hudson Railway |
| DPDZ | Delaware and Hudson Railway Company Incorporated |
| DPGX | DuPont (Tractech Systems) |
| DPIX | Dufour Petroleum |
| DPIX | Dufour Petroleum Incorporated |