| Abbreviation | Definition |
|---|---|
| CMC | CMC Railroad Incorporated |
| CMCU | Crowley Maritime Corporation |
| CMCX | CMC Railroad (Sweetman Construction) |
| CMCX | Sweetman Construction Company |
| CMCZ | Crowley Maritime Corporation |
| CMDX | Cargill |
| CMDX | Cargill Incorporated |
| CMER | Curtis, Milburn and Eastern Railroad |
| CMEX | CEMEX |
| CMG | Chicago, Milwaukee and Gary Railway |
| CMGN | Central Michigan Railway |
| CMGN | Central Michigan Railway Company |
| CMHX | CarMath |
| CMHX | CarMath Incorporated |
| CMIU | Intermobile Container LLC |
| CMIX | Consolidated Minerals |
| CMIX | Consolidated Minerals Incorporated |
| CMLU | Containers Marine Lines |
| CMLU | Containers Marine Lines (Division of American Export) |
| CMLX | Craggy Mountain Line |