| Abbreviation | Definition |
|---|---|
| CLPX | Boulder Scientific |
| CLPX | Boulder Scientific Company |
| CLPZ | Clarendon and Pittsford Railroad |
| CLPZ | Clarendon and Pittsford Railroad Company |
| CLRL | Central Light Rail Line |
| CLRL | Cross London Rail Links |
| CLRX | Clayton Rail |
| CLSL | Columbia and Silver Creek Railroad |
| CLSX | Cargill Incorporated - Salt Division |
| CLSX | Cargill Salt Division |
| CLTU | Chemical Leaman Tank Lines |
| CLTU | Chemical Leaman Tank Lines Incorporated |
| CLTX | Cloro de Tehuantepec de CV |
| CLTX | Cloro de Tehuantepec S. A. de C. V. |
| CM | Central Montana Rail |
| CM | Central Montana Rail Incorporated |
| CMAU | CMA CGM |
| CMBU | CMB |
| CMBU | Cmb Sa |
| CMC | CMC Railroad |