| 1 | CLC | Classic Air AG | Callsign: Classic Air, | CH | AVCODES |
| 2 | CLC | Columbia & Cowlitz Ry. Co. | 1/1975-7/2005 | | NAKINA |
| 3 | CLC | Columbia & Cowlitz Ry. Co. | 1/75-7/2000 | | NRHS |
| 4 | CLC | COLUMBIA & COWLITZ RAILWAY COMPANY | | | PWRC |
| 5 | CLC | Columbia and Cowlitz Railway | | | RSRV |
| 6 | CLC | Columbia and Cowlitz | | USA | TRAFFIC |
| 7 | CLCB | CLYDES CUSTOM BODY & PAINT | | | SCAC3 |
| 8 | CLCC | CLUTCH CARGO INTERNATIONAL INC | | | SCAC3 |
| 9 | CLCC | CLUTCH GLOBAL LOGISTICS | | | SCAC4 |
| 10 | CLCD | CALIFORNIA CONSOLIDATED ENTERPRISES | | | SCAC3 |
| 11 | CLCD | CL CONSOLIDATORS SERVICES LTD | | | SCAC4 |
| 12 | CLCF | CALICO FUELS INC | | | SCAC3 |
| 13 | CLCF | COOL CREEK FARM | | | SCAC4 |
| 14 | CLCG | COLLINS CARTAGE CORP | | | SCAC3 |
| 15 | CLCH | CLINCH CO INC | | | SCAC3 |
| 16 | CLCI | CLINTON CARTAGE INC | | | SCAC3 |
| 17 | CLCJ | CLAYCON TRANSPORTS CORPORATION | | | SCAC3 |
| 18 | CLCL | CLIPPER CARLOADING CO | | | PWRC |
| 19 | CLCL | CLIPPER CARLOADING COMPANY | | | SCAC3 |
| 20 | CLCN | CLARK COUNTY WHOLESALE INC | | | SCAC3 |
| 21 | CLCN | CLIENT CONNECTION INC | | | SCAC4 |
| 22 | CLCO | Claremont and Concord Ry. Co., Inc. | 7/1965-10/1966 & 1/1975-1/1980; eliminated 1/1989 | | NAKINA |
| 23 | CLCO | Claremont and Concord Ry. Co., Inc. | 7/65-10/66 & 1/75-1/80; eliminated 1/89 | | NRHS |
| 24 | CLCO | CLAREMONT & CONCORD RAILWAY | | | PWRC |
| 25 | CLCO | Claremont and Concord Railway | | | RSRV |
| 26 | CLCO | CLINCH CO INC | | | SCAC4 |
| 27 | CLCO | Classi Coach | | USA | TRAFFIC |
| 28 | CLCQ | CAROLINA MIRROR CORPORATION | | | SCAC3 |
| 29 | CLCQ | CHAPMAN/LEONARD STUDIO EQUIPMENT IN | | | SCAC4 |
| 30 | CLCR | CONTINENTAL LEASING CORPORATION | | | SCAC3 |
| 31 | CLCR | CONSOLIDATED LOGISTICS CENTER | | | SCAC4 |
| 32 | CLCS | CLASSIC CARTAGE | | | SCAC3 |
| 33 | CLCS | CLINE COACHES | | | SCAC4 |
| 34 | CLCT | CRI LOGISTICS LLC | | | SCAC4 |
| 35 | CLCU | CARU PRAHA S.R.O | | CZ | BIC |
| 36 | CLCU | NORTH AFRICA SHIPPING CO., LTD | | | SCAC3 |
| 37 | CLCU | CATU PRAHA S R O | | | SCAC4 |
| 38 | CLCV | CLAUSEN CONSTRUCTION INC | | | SCAC3 |
| 39 | CLCV | CLT CONTRACTING | | | SCAC4 |
| 40 | CLCW | CLEAR LAKE TRUCK & CRANE INC | | | SCAC3 |
| 41 | CLCX | Chattahoochie Locomotive Co., Inc. | 7/2005 (not listed) | | NAKINA |
| 42 | CLCX | Unocal Petroleum Products & Chemicals Division, Union Oil Co. of California | added 7/1994 | | NAKINA |
| 43 | CLCX | Unocal Chemicals Division, Union Oil Co. of California | added 1/1987; 1/1994; eliminated 7/1994 | | NAKINA |
| 44 | CLCX | Union Chemicals Division, Union Oil Co. of California | added 7/1978; 1/1980; eliminated 1/1987 | | NAKINA |
| 45 | CLCX | Collier Carbon and Chemical Corp. | added 10/1966; 10/1966-1/1975; eliminated 7/1978 | | NAKINA |
| 46 | CLCX | Cornwell Chemical Corp. | 1/1952-7/1954; eliminated 10/1954 | | NAKINA |
| 47 | CLCX | General American Transportation Corp. | 1/1945-1/1946 | | NAKINA |
| 48 | CLCX | Commercial Molasses Corp. | 7/1937-1/1943 | | NAKINA |
| 49 | CLCX | Commercial Car Line | 8/1920-7/1935 | | NAKINA |
| 50 | CLCX | Commercial Molasses Corp. | Apr-38 | | NRHS |
| 51 | CLCX | Cornwell Chemical Corp. | Jan-52 | | NRHS |
| 52 | CLCX | Collier Carbon and Chemical Corp. | added 10/66; 10/66-1/75; eliminated 7/78 | | NRHS |
| 53 | CLCX | Union Chemicals Division, Union Oil Co. of California | added 7/78; 1/80; eliminated 1/87 | | NRHS |
| 54 | CLCX | Unocal Chemicals Division, Union Oil Co. of California | added 1/87; 1/94; eliminated 7/94 | | NRHS |
| 55 | CLCX | Unocal Petroleum Products & Chemicals Division, Union Oil Co. of California | added 7/94 | | NRHS |
| 56 | CLCX | *COMMERCIAL CAR LINE | | | PWRC |
| 57 | CLCX | *COMMERCIAL MOLASSES CORP. | | | PWRC |
| 58 | CLCX | *GENERAL AMERICAN TRANSPORTATION CORP. | | | PWRC |
| 59 | CLCX | *CHATAHOOCHEE LOCOMOTIVE COMPANY | | | PWRC |
| 60 | CLCX | *UNOCAL CHEMICALS DIVISION, UNION OIL CO. OF CALIF. [COLLIER CARBON & CHEMICAL GROUP] | | | PWRC |
| 61 | CLCX | +CLCX, INC. | | | PWRC |
| 62 | CLCX | Chatahoochee Locomotive | | | RSRV |
| 63 | CLCX | CHATTAHOOCHEE LOCOMOTIVE COMPANY IN | | | SCAC4 |
| 64 | CLCZ | *COMPLETE LOGISTICS COMPANY | | | PWRC |
| 65 | CLCZ | *COSGROVE LEAD CO. | | | PWRC |
| 66 | CLCZ | Complete Logistics | | | RSRV |
| 67 | CLCZ | COMPLETE LOGISTICS COMPANY | | | SCAC4 |