| 1 | CIW | Civair Airways | Callsign: Civflight, | ZA | AVCODES |
| 2 | CIW | Afrik Airways | | CI | AVCODES |
| 3 | CIW | Civair Airways | | | ICAO1 |
| 4 | CIW | Illinois Central R.R. Co. | added 4/1988; 1/1994-7/2005 | | NAKINA |
| 5 | CIW | Illinois Central Gulf R.R. Co. | added 7/1983; eliminated 4/1988 | | NAKINA |
| 6 | CIW | Chicago & Illinois Western R.R. | 1/1941-10/1966 & 1/1975-1/1980; eliminated 1/1981 | | NAKINA |
| 7 | CIW | Chicago & Illinois Western R.R. Co. | added 1/1981; eliminated 7/1983 | | NAKINA |
| 8 | CIW | Chicago & Illinois Western R.R. | 10/57-10/66 & 1/75-1/80; eliminated 1/81 | | NRHS |
| 9 | CIW | Chicago & Illinois Western R.R. Co. | added 1/81 | | NRHS |
| 10 | CIW | Illinois Central Gulf R.R. Co. | eliminated 4/88 | | NRHS |
| 11 | CIW | Illinois Central R.R. Co. | added 4/88; 1/94-7/2000 | | NRHS |
| 12 | CIW | ILLINOIS CENTRAL RAILROAD [CHICAGO & ILLINOIS WESTERN RR] | | | PWRC |
| 13 | CIW | Illinois Central Gulf (Canadian National Railway) | | | RSRV |
| 14 | CIW | Chicago & Illinois Western | | USA | TRAFFIC |
| 15 | CIWE | CAM II WAREHOUSE | | | SCAC4 |
| 16 | CIWH | CRESCENT CITY TRANSPORTATION & WARE | | | SCAC4 |
| 17 | CIWI | COLLINS INDUSTRIAL WAREHOUSE | | | SCAC3 |
| 18 | CIWL | Compagnie International de Wagon Lits | | X | TRAFFIC |
| 19 | CIWL | Compagnie des Wagon-Lits | | BE | VKM |
| 20 | CIWN | The Cincinnati, Indianapolis & Western R.R. Co. | 8/1920-7/1923 | | NAKINA |
| 21 | CIWN | The Cincinnati, Indianapolis & Western R.R. Co. | 23-Jul | | NRHS |
| 22 | CIWN | CINCINNATI, INDIANAPOLIS & WESTERN RAILROAD CO. | | | PWRC |
| 23 | CIWQ | CAIN WAREHOUSE CO | | | SCAC3 |
| 24 | CIWR | CIRCLE W TRUCKING INC | | | SCAC4 |
