| 1 | CSO | Casino Airlines, Inc. | Callsign: Casair, | USA | AVCODES |
| 2 | CSO | Casino Airline | | | ICAO1 |
| 3 | CSO | Connecticut Southern R.R. Inc. | added 4/1997; 7/2000-7/2005 | | NAKINA |
| 4 | CSO | Connecticut Southern R.R. Inc. | added 4/97; 7/2000 | | NRHS |
| 5 | CSO | CONNECTICUT SOUTHERN RAILROAD | | | PWRC |
| 6 | CSO | Connecticut Southern Railroad | | | RSRV |
| 7 | CSO | CONNECTICUT SOUTHERN RAILROAD INC | | | SCAC4 |
| 8 | CSO | Connecticut Southern Railroad | | USA | TRAFFIC |
| 9 | CSOB | CUSTOM TOURS & TRANSPORTATION | | | SCAC3 |
| 10 | CSOC | CASON BUILDERS SUPPLY INC | | | SCAC3 |
| 11 | CSOC | CASON BUILDERS SUPPLY | | | SCAC4 |
| 12 | CSOD | CARRASCO TRUCKING | | | SCAC3 |
| 13 | CSOE | CROSS OIL COMPANY | | | SCAC3 |
| 14 | CSOF | CARR & SONS INC | | | SCAC3 |
| 15 | CSOG | CARNEY & SON TRUCKING SERVICES INC | | | SCAC3 |
| 16 | CSOH | CARSTENSEN & SONS TRUCKING INC | | | SCAC3 |
| 17 | CSOI | CARLSON, JOEL TRUCKING INC | | | SCAC3 |
| 18 | CSOJ | CENTRAL & SOUTHERN TRANSPORT INC | | | SCAC3 |
| 19 | CSOJ | CLASSICAL THEATRE PROJECT | | | SCAC4 |
| 20 | CSOK | CUSTOM TRUCK | | | SCAC3 |
| 21 | CSOK | CARGO SOLUTIONS | | | SCAC4 |
| 22 | CSOL | CHEETAH SHIPPING CO LTD | | | SCAC3 |
| 23 | CSOM | CUSTOM SERVICES | | | SCAC3 |
| 24 | CSOM | CANYON STATE OIL CO INC | | | SCAC4 |
| 25 | CSOM | Csömödér | Real: CAEV | H | TRAFFIC |
| 26 | CSON | CONSUMERS OIL CORPORATION | | | SCAC4 |
| 27 | CSOO | CONSOLIDATED CONTAINER CORPORATION | | | SCAC3 |
| 28 | CSOO | CAROUSEL SOFTOYS INC | | | SCAC4 |
| 29 | CSOP | CARSON OIL COMPANY | | | SCAC3 |
| 30 | CSOP | CARSON OIL COMPANY INC | | | SCAC4 |
| 31 | CSOQ | C & T TRANSPORT SERVICES CO | | | SCAC4 |
| 32 | CSOR | Connecticut Southern Railroad | | | RSRV |
| 33 | CSOR | CHASSILORS INC | | | SCAC3 |
| 34 | CSOS | CASTILLO, MARMOLES | | | SCAC4 |
| 35 | CSOT | CARLSON TRUCKING | | | SCAC3 |
| 36 | CSOT | CRISCO TRANSIT INC | | | SCAC4 |
| 37 | CSOU | CMA-CGM | | F | BIC |
| 38 | CSOU | CAZENOVIA SOUTHERN RAILROAD | | | PWRC |
| 39 | CSOU | CONTAINER MARKETING (OVESEAS) LTD | | | SCAC3 |
| 40 | CSOU | CONTAINER MARKETING (OVERSEAS) LTD | | | SCAC4 |
| 41 | CSOV | CASH & SON CARTAGE AGENT | | | SCAC3 |
| 42 | CSOW | C & S TOWING SERVICE INC | | | SCAC3 |
| 43 | CSOW | CS LOGISTICS | | | SCAC4 |
| 44 | CSOX | CITGO Petroleum Corp. | added 7/1983; 1/1994-7/2005 | | NAKINA |
| 45 | CSOX | Cities Service Co., Petroleum Products Group | added 1/1981; eliminated 7/1983 | | NAKINA |
| 46 | CSOX | Cities Service Pipe Line Co. | added 4/1979; 1/1980; eliminated 1/1981 | | NAKINA |
| 47 | CSOX | Cities Service Co. | added 4/1978; eliminated 4/1979 | | NAKINA |
| 48 | CSOX | Cities Service Pipe Line Co. | added 10/1967; 4/1970-1/1975; eliminated 4/1978 | | NAKINA |
| 49 | CSOX | Cities Service Oil Co. | added 4/1963; 7/1965-10/1966; eliminated 10/1967 | | NAKINA |
| 50 | CSOX | Cities Service Petroleum Co. | added 7/1962; eliminated 4/1963 | | NAKINA |
| 51 | CSOX | Cities Service Oil Co. | 7/1937-4/1961; eliminated 7/1962 | | NAKINA |
| 52 | CSOX | Cities Service Oil Co. of Ohio | 7/1930 | | NAKINA |
| 53 | CSOX | Cities Service Oil Co. of Pennsylvania | Apr-38 | | NRHS |
| 54 | CSOX | Cities Service Oil Co. | 1/52-10/66; eliminated 10/67 | | NRHS |
| 55 | CSOX | Cities Service Pipe Line Co. | added 10/67; 4/70-1/75; eliminated 4/78 | | NRHS |
| 56 | CSOX | Cities Service Co. | added 4/78; eliminated 4/79 | | NRHS |
| 57 | CSOX | Cities Service Pipe Line Co. | added 4/79; 1/80; eliminated 1/81 | | NRHS |
| 58 | CSOX | Cities Service Co., Petroleum Products Group | added 1/81 | | NRHS |
| 59 | CSOX | CITGO Petroleum Corp. | 1/94-7/2000 | | NRHS |
| 60 | CSOX | CITGO PETROLEUM CORP. [CITIES SERVICE OIL CO.] | | | PWRC |
| 61 | CSOX | CITGO Petroleum Corporation | | | RSRV |
| 62 | CSOX | CITIES SERVICE PIPELINE CO | | | SCAC3 |
| 63 | CSOX | CITGO PETROLEUM CORP | | | SCAC4 |
| 64 | CSOY | CASA OVERSEAS LTD | | | SCAC3 |
| 65 | CSOY | CONTAINERSHIPS LTD OY | | | SCAC4 |
