| 1 | CLX | Cargolux Airlines International, S.A. | IATA: CV, Callsign: Cargolux, IATA Prefix: 172, | L | AVCODES |
| 2 | CLX | Cargolux | IATA: CV | | ICAO1 |
| 3 | CLX | Crossett Lumber Co. | 1/1945 (not listed); 1/1946-1/1952; eliminated 10/1953 | | NAKINA |
| 4 | CLX | Cities Service Oil Co. | 7/1937-4/1938 | | NAKINA |
| 5 | CLX | Crew Levick Co. | 8/1920-7/1935 | | NAKINA |
| 6 | CLX | Crew Levick Co. (The Cities Service Oil Co. of Pennsylvania) | Apr-38 | | NRHS |
| 7 | CLX | Crossett Lumber Co. | 1/52; eliminated 10/53 | | NRHS |
| 8 | CLX | *CREW LEVICK CO. | | | PWRC |
| 9 | CLX | *CITIES SERVICE OIL CO. | | | PWRC |
| 10 | CLX | *CROSSET LUMBER CO. | | | PWRC |
| 11 | CLXD | CLIMATE EXPRESS INC | | | SCAC4 |
| 12 | CLXE | CALEX EXPRESS INC | | | SCAC3 |
| 13 | CLXE | CALEX EXPRESS INC | | | SCAC4 |
| 14 | CLXF | CALEXICO FREIGHT LINES | | | SCAC4 |
| 15 | CLXG | CST LOGISTICS INC | | | SCAC4 |
| 16 | CLXH | CENTRAL TAXI DISPATCH INC | | | SCAC3 |
| 17 | CLXH | C & L TRANSPORT INC | | | SCAC4 |
| 18 | CLXI | CAL-EXPRESS INC | | | SCAC3 |
| 19 | CLXJ | CALTREX INC | | | SCAC4 |
| 20 | CLXK | CL TRANSPORTATION LLC | | | SCAC4 |
| 21 | CLXL | CONTINENTAL EXPRESS LINES INC | | | SCAC3 |
| 22 | CLXL | CONTINENTAL EXPRESS LINES INC | | | SCAC4 |
| 23 | CLXM | C & L MOVING & STORAGE INC | | | SCAC3 |
| 24 | CLXM | C & L MOVING & STORAGE INC | | | SCAC4 |
| 25 | CLXN | CLEAN CAR CONNEXION INC | | | SCAC4 |
| 26 | CLXO | C L TRANSPORT | | | SCAC4 |
| 27 | CLXQ | C & L LOGISTICS INC | | | SCAC4 |
| 28 | CLXR | COLE COUNTRY EXPRESS INC | | | SCAC3 |
| 29 | CLXS | COAST LINE EXPRESS CO | | | SCAC3 |
| 30 | CLXS | COAST LINE EXPRESS CO | | | SCAC4 |
| 31 | CLXU | AMPLE HARVEST CONTAINER FUND SPC | | CAY | BIC |
| 32 | CLXU | CONTAINER LEASING A/S | | | SCAC4 |
| 33 | CLXV | COOOL EXPRESS INC | | | SCAC4 |
| 34 | CLXW | COOLX INC | | | SCAC3 |
| 35 | CLXY | COASTLINE TRANSPORTATION INC | | | SCAC4 |
