| 5001 | GROX | USL Capital Rail Services | added 4/1994; eliminated 10/1996 | | NAKINA |
| 5002 | GROX | U.S. Rail Services, Inc. | added 1/1993; 1/1994; eliminated 4/1994 | | NAKINA |
| 5003 | GROX | Chrysler Rail Transportation Corp. | eliminated 1/1993 | | NAKINA |
| 5004 | GROX | Growth Nonstock Cooperative, Inc. | added 7/1980; eliminated 10/1988 | | NAKINA |
| 5005 | GROX | Georgia Rosin Products Co. | 8/1920-4/1947 | | NAKINA |
| 5006 | GROX | Georgia Rosin Products Co. | Apr-38 | | NRHS |
| 5007 | GROX | Growth Nonstock Cooperative, Inc. | added 7/80; eliminated 10/88 | | NRHS |
| 5008 | GROX | Chrysler Rail Transportation Corp. | eliminated 1/93 | | NRHS |
| 5009 | GROX | U.S. Rail Services, Inc. | added 1/93; 1/94; eliminated 4/94 | | NRHS |
| 5010 | GROX | USL Capital Rail Services | added 4/94; eliminated 10/96 | | NRHS |
| 5011 | GROX | First Union Rail | added 10/96; 7/2000 | | NRHS |
| 5012 | GROX | *GEORGIA ROSIN PRODUCTS CO. | | | PWRC |
| 5013 | GROX | +FIRST UNION RAIL[(RUSX) USL CAPITAL RAIL SERVICES; CHRYSLER RAIL TRANSPORTAION CORP.; GROWTH NONSTOP COOPERATIVE] | | | PWRC |
| 5014 | GROX | Growth Nonstop Cooperative (First Union Rail) | | | RSRV |
| 5015 | GRP | Ozark Air Lines, Inc. d/b/a/ Great Plains Airlines | IATA: ZO, Callsign: Great Plains, Name changed from Ozark Air Lines, Inc. Founded in 2001. Ceased operations in 2004. ICAO designator changed from OZR | USA | AVCODES |
| 5016 | GRP | Gryphon Air, LLC | Callsign: Air Fox, | USA | AVCODES |
| 5017 | GRP | Great Plains Airlines | | | ICAO1 |
| 5018 | GRPE | GRAPHIC ARTS EXPRESS INC | | | SCAC4 |
| 5019 | GRPI | GRESS POULTRY INC | | | SCAC4 |
| 5020 | GRPJ | GROUPE TRANSTECK INC | | | SCAC4 |
| 5021 | GRPL | GRISHAM PETROLEUM INC | | | SCAC4 |
| 5022 | GRPN | G R P I T INC | | | SCAC4 |
| 5023 | GRPO | GREEN PETROLEUM CO | | | SCAC4 |
| 5024 | GRPQ | GENERAL TRANSPORT INC | | | SCAC4 |
| 5025 | GRPT | Grande Prairie Transit | | CG | TRAFFIC |
| 5026 | GRPU | TRISTAR ENGINNERING CONSULTING LOGISTIC SA | | CH | BIC |
| 5027 | GRPU | GRP MULTI-LOGISTICS SA | | | SCAC4 |
| 5028 | GRPV | GROUP PETROLEUM SERVICES INC | | | SCAC4 |
| 5029 | GRPX | The CIT Group/Capital Finance, Inc. | added 10/1999; 7/2000-7/2005 | | NAKINA |
| 5030 | GRPX | General Chemical (Soda Ash) Partners | added 7/1987; 1/1994; eliminated 10/1999 | | NAKINA |
| 5031 | GRPX | General Chemical (Soda Ash) Partners | added 7/87; 1/94; eliminated 10/99 | | NRHS |
| 5032 | GRPX | The CIT Group/Capital Finance, Inc. | added 10/99; 7/2000 | | NRHS |
| 5033 | GRPX | CIT GROUP/CAPITAL FINANCE (GENERAL CHEMICAL (SODA ASH) PARTNERS, LESSEE) | | | PWRC |
| 5034 | GRPX | General Chemical (CIT Financial) | | | RSRV |
| 5035 | GRPX | CIT GROUP/CAPITAL FINANCE INC, THE | | | SCAC4 |
| 5036 | GRPX | General Chemical (Soda Ash) Partners | | USA | TRAFFIC |
| 5037 | GRPY | GRP INC | | | SCAC4 |
| 5038 | GRPZ | GREAT LAKES CARBON PLANT | | | PWRC |
| 5039 | GRQA | GRABOWSKI, ROD TRUCKING | | | SCAC4 |
| 5040 | GRQC | GRAHAM, RALPH EQUIPMENT CO | | | SCAC4 |
| 5041 | GRQD | GRAHAM, D TRANSPORT INC | | | SCAC4 |
| 5042 | GRQR | GREYSTONE CARRIERS INC | | | SCAC4 |
| 5043 | GRQS | GRANT STREET SERVICES INC | | | SCAC4 |
| 5044 | GRR | Agroar - Trabalhos Aereos | | | ICAO1 |
| 5045 | GRR | Georgetown R.R. Co. | 1/1975-7/2000; eliminated 10/2001; added 10/2003; eliminated 4/2004; added 7/2005; 7/2005; eliminated 1/2006 | | NAKINA |
| 5046 | GRR | Georgetown R.R. Co. | 1/75-7/2000 | | NRHS |
| 5047 | GRR | GEORGETOWN RAILROAD CO. | | | PWRC |
| 5048 | GRR | Georgetown Railroad | | | RSRV |
| 5049 | GRR | Georgetown Railroad Company | | USA | TRAFFIC |
| 5050 | GRRA | GRAND RAPIDS TRANSFER AND STORAGE, | | | SCAC4 |
| 5051 | GRRB | GRIMM, RICHARD R | | | SCAC4 |
| 5052 | GRRD | GRUPO RAMSA DE MATAMOROS | | | SCAC4 |
| 5053 | GRRF | GARCIA RUVALCALBA, FLORENCIO | | | SCAC4 |
| 5054 | GRRG | GRUPO REFRIGERADOS DEL SUR | | | SCAC4 |
| 5055 | GRRI | G A R R TRUCKLINES | | | SCAC4 |
| 5056 | GRRJ | GUNVILLE TRUCKING | | | SCAC4 |
| 5057 | GRRK | GRAY ROCK FARMS INC | | | SCAC4 |
| 5058 | GRRM | GREENTREE TRANSPORTATION CO | | | SCAC1 |
| 5059 | GRRM | GREENTREE TRANSPORTATION | | | SCAC4 |
| 5060 | GRRO | GUERRERO GUERRERO, JOSE DANIEL | | | SCAC4 |
| 5061 | GRRQ | GREATER TATER | | | SCAC4 |
| 5062 | GRRT | Grand River Transit | | CDN | TRAFFIC |
| 5063 | GRRU | GRANDEE PTE LTD | | | SCAC4 |
| 5064 | GRRW | GARROW OIL MARKETING INC | | | SCAC4 |
| 5065 | GRRX | Wampum Hardware | 1/1994-7/2005 (not listed) | | NAKINA |
| 5066 | GRRX | Good Rich Refining Co., Ltd. | 1/1945-4/1947 | | NAKINA |
| 5067 | GRRX | O.E. Linsin, Inc. | 7/1937 | | NAKINA |
| 5068 | GRRX | The Golden Rule Refining Co. | 8/1920-7/1935 | | NAKINA |
| 5069 | GRRX | Wampum Hardware | 1/94-7/2000 | | NRHS |
| 5070 | GRRX | *GOOD RICH REFINING CO. [O.E. LINSIN, INC.; GOLDEN RULE REFINING CO.] | | | PWRC |
| 5071 | GRRX | +WAMPUM HARDWARE COMPANY | | | PWRC |
| 5072 | GRRX | Good Rich Refining (Wampum Hardware) | | | RSRV |
| 5073 | GRRY | GREENBRIER RIVER RAILWAY | | | PWRC |
| 5074 | GRRZ | GENEVA RAILROAD | | | PWRC |
| 5075 | GRS | Golden Rule Airlines | | | ICAO1 |
| 5076 | GRS | GUILFORD RAILROAD SYSTEM | | | PWRC |
| 5077 | GRS | Guilford Rail System | Pan Am Railways | USA | TRAFFIC |
| 5078 | GRSB | GLEN ROSE TRANSPORTATION | | | SCAC4 |
| 5079 | GRSC | GRESS TRUCKING | | | SCAC4 |
| 5080 | GRSD | GANADERA REBEIL SPR DE RL | | | SCAC4 |
| 5081 | GRSE | GARRISON TRANSPORTATION SERVICES IN | | | SCAC4 |
| 5082 | GRSE | Granit Srevices | | FR | VKM |
| 5083 | GRSF | GST CORPORATION (INTERMODAL DIVISIO | | | SCAC4 |
| 5084 | GRSJ | GROSSMAN, R TRUCKING CO LLC | | | SCAC4 |
| 5085 | GRSK | GREENSTATE TRUCKING INC | | | SCAC4 |
| 5086 | GRSM | GREAT SMOKEY MOUNTAIN RAILROAD | | | PWRC |
| 5087 | GRSM | GRASSMID TRANSPORT | | | SCAC4 |
| 5088 | GRSQ | GLOBAL REFRIGERATION SOLUTIONS | | | SCAC4 |
| 5089 | GRST | GARST LP GAS INC | | | SCAC4 |
| 5090 | GRST | Gräf & Stift | since 2002 subsidiary of MAN | A | TRAFFIC |
| 5091 | GRSU | GREEN SEA TRANSPORT LLC | | RUS | BIC |
| 5092 | GRSU | GRENCO REEFER SERVICES LTD | | | SCAC4 |
| 5093 | GRSV | GRAEBEL RELOCATION SERVICES WORLDWI | | | SCAC4 |
| 5094 | GRSW | GRIMSHAW TRUCKING | | | SCAC4 |
| 5095 | GRSX | Gunderson Rail Services | added 7/2000; 7/2000-7/2005; eliminated 10/2009 | | NAKINA |
| 5096 | GRSX | National Car Co. | 4/1947-1/1952 | | NAKINA |
| 5097 | GRSX | National Car Co. | Jan-52 | | NRHS |
| 5098 | GRSX | Gunderson Rail Services | added 7/2000; 7/2000 | | NRHS |
| 5099 | GRSX | *NATIONAL CAR CO. | | | PWRC |
| 5100 | GRSX | *GARLAND RAILROAD SRUR TRACK | | | PWRC |
