| Abbreviation | Definition |
|---|---|
| JTMX | JTM Industries Incorporated |
| JTPX | Joseph Transportation |
| JTSX | Joseph Transportation |
| JTSZ | Jontri Transportation |
| JTSZ | Jontri Transportation Company |
| JTTX | Trailer Train (TTX Corporation) |
| JTTX | TTX Company |
| JUGU | Jogolinja |
| JURT | Josh Urban Rail Tour |
| JVR | Junction Valley Railroad |
| JVRR | Juniata Valley Railroad |
| JVRR | Juniata Valley Railroad Company |
| JWAX | GE Rail Services Corporation |
| JWAX | General Electric Railcar Services Corporation |
| JWFX | J. W. Flammer |
| JWRX | Alabama Power Company |
| JWRX | Jim Walter Resources (Alabama Power) |
| KABX | Canadian Resource Distribution Incorporated |
| KABX | Kaber Canadian Resource Distribution |
| KACX | Kaiser Aluminum and Chemical Corporation |