| Abbreviation | Definition |
|---|---|
| DCMX | Davidson Construction Materials |
| DCON | Detroit Connecting Railroad |
| DCOU | Dow Corning Corporation |
| DCPX | Dart Container Corporation of Pennsylvania |
| DCR | Delray Connecting Railroad |
| DCRA | Dulles Corridor Rail Association |
| DCRR | Dubois County Railroad |
| DCSU | Delta Conteneur Service |
| DCTX | PLM International |
| DCTX | PLM International Incorporated |
| DDDX | Frontier Cooperative |
| DDDX | Frontier Cooperative Company |
| DDEX | Dupont Dow Elastomers |
| DDEX | Dupont Dow Elastomers L.L.C. |
| DDNX | Didion |
| DDNX | Didion Incorporated |
| DEBX | Ceres AG Products |
| DEC | Delhi Cantt |
| DEEX | Detroit Edison |
| DEEX | Detroit Edison Company |