| 1 | GCO | Gemini Air Cargo LLC | IATA: GR, Callsign: Gemini, IATA Prefix: 358, Ceased operations on 12 August 2008 | USA | AVCODES |
| 2 | GCO | Gemini Air Cargo | IATA: GR | | ICAO1 |
| 3 | GCOC | GAGE COUNTY OIL CO INC | | | SCAC4 |
| 4 | GCOD | GILCO TRANSPORTATION INC | | | SCAC4 |
| 5 | GCOF | GREENWOOD CONSTRUCTION | | | SCAC4 |
| 6 | GCOH | GIRAN CORPORATION | | | SCAC4 |
| 7 | GCOI | GATEWEST STAMP & COIN LTD | | | SCAC4 |
| 8 | GCOK | GILCO TRUCKING COMPANY INC | | | SCAC4 |
| 9 | GCOM | GRACE OIL COMPANY INC | | | SCAC4 |
| 10 | GCOQ | GASCO ENERGY SUPPLY LLC | | | SCAC4 |
| 11 | GCOS | GILB TRUCKING LLC | | | SCAC4 |
| 12 | GCOU | GASCO N V | | | SCAC4 |
| 13 | GCOX | The Gold Coast Railroad Museum Inc. | 7/2005 (not listed) | | NAKINA |
| 14 | GCOX | Gulf Oil Products Co., Division of Gulf Oil Corp. | eliminated 7/1985 | | NAKINA |
| 15 | GCOX | Miller Compressing Co. | added 10/1964; 7/1965-4/1970; eliminated 1/1973 | | NAKINA |
| 16 | GCOX | Miller Compressing Co. | 7/65-4/70; eliminated 1/73 | | NRHS |
| 17 | GCOX | *MILLER COMPRESSING CO. [RETIRED 10-28-93 ATP] | | | PWRC |
| 18 | GCOX | *GULF OIL PRODUCTS CO. DIV. GULF OIL CORP. | | | PWRC |
| 19 | GCOX | +GOLD COAST RAILROAD MUSEUM, INC. | | | PWRC |
| 20 | GCOX | Gold Coast Railroad Museum | | | RSRV |
| 21 | GCOX | GOLD COAST RAILROAD MUSEUM INC, THE | | | SCAC4 |
| 22 | GCOZ | GREENWAY CO-OP | | | PWRC |
