| 4001 | DOWX | The Dow Chemical Co. | 8/1920-7/2005 | | NAKINA |
| 4002 | DOWX | The Dow Chemical Co. | 4/38-7/2000 | | NRHS |
| 4003 | DOWX | DOW CHEMICAL CO. | | | PWRC |
| 4004 | DOWX | Dow Chemical | | | RSRV |
| 4005 | DOWX | Dow Chemicals | | USA | TRAFFIC |
| 4006 | DOX | Derby Refining Co. | added 4/1955; 10/1957; eliminated 1/1960 | | NAKINA |
| 4007 | DOX | Derby Oil Co. | 1/1950-7/1954; eliminated 4/1955 | | NAKINA |
| 4008 | DOX | General American Transportation Corp. | 4/1938 | | NAKINA |
| 4009 | DOX | The Derby Oil Co. | 8/1920-7/1937 | | NAKINA |
| 4010 | DOX | Derby Oil Co. (General American Transportation Corp.) | Apr-38 | | NRHS |
| 4011 | DOX | Derby Oil Co. | 1/52; eliminated 4/55 | | NRHS |
| 4012 | DOX | Derby Refining Co. | added 4/55; 10/57; eliminated 1/60 | | NRHS |
| 4013 | DOX | DERBY REFINING CO. (GENERAL AMERICAN TRANSPORTATION CORP.) [DERBY OIL CO.] | | | PWRC |
| 4014 | DOXE | DIXIE OHIO XPRESS | | | SCAC4 |
| 4015 | DOXM | DOX | | | SCAC4 |
| 4016 | DOXT | DOMINO TRANSPORT INC | | | SCAC4 |
| 4017 | DOXY | DIXIE OHIO EXPRESS INC | | | PWRC |
| 4018 | DOYB | DOYLE, BRANT INC | | | SCAC4 |
| 4019 | DOYE | DOYLE TRANSPORTATION | | | SCAC4 |
| 4020 | DOYS | DOYLE SIMS & SONS TRUCKING INC | | | SCAC4 |
| 4021 | DOYT | DOYLE TRANSPORT INC | | | SCAC4 |
| 4022 | DOZEM | dornburger zement GmbH & Co. KG | | DE | VKM |
| 4023 | DOZO | DOZIER OIL COMPANY | | | SCAC4 |
| 4024 | DP | Air 2000 Ltd. | ICAO: AMM, Callsign: Jetset, IATA Prefix: 091, Name changed to First Choice Airways Ltd. | GB | AVCODES |
| 4025 | DP | Dunlop Rubber Company Ltd. (Aviation Division) | Callsign: Dunlop, | GB | AVCODES |
| 4026 | DP | First Choice Airways Limited. | ICAO: AMM, Callsign: Jetset, IATA Prefix: 091, Name changed from Air 2000 Ltd. ICAO designator will change to FCA w.e.f. 14 January 2003. | GB | AVCODES |
| 4027 | DP | Air Sinai | ICAO: ASD, Callsign: Air Sinai, Designator DP recalled by IATA | ET | AVCODES |
| 4028 | DP | First Choice Airways Limited | ICAO: FCA, Callsign: Jetset, IATA Prefix: 091, Merged with Thomsonfly Ltd to form Thomson Airways Ltd on 01 November 2008. Name changed from Air 2000 Ltd. ICAO designator will change from AMM w.e.f. 14 January 2003. | GB | AVCODES |
| 4029 | DP | Pobeda Airlines LLC | ICAO: PBD, Callsign: Pobeda, Founded on 16 September 2014. Commenced operations on 01 December 2014. Low cost subsidary of Aeroflot | RUS | AVCODES |
| 4030 | DP | Deer Park Ry. (Co.) | 7/1935-7/1954 | | NAKINA |
| 4031 | DP | Deer Park Ry. | 4/38-1/52 | | NRHS |
| 4032 | DP | Deutsche Privatbahn GmbH | Hameln | D | privat-bahn.de |
| 4033 | DP | DEER PARK RAILWAY | | | PWRC |
| 4034 | DP | Deutsche Post (DDR) | | DDR | TRAFFIC |
| 4035 | DP | DP Deutsche Privatbahn GmbH | | DE | VKM |
| 4036 | DP01 | (RAIL) CSD-DEPRE PRODUCT | | | PWRC |
| 4037 | DP02 | (RAIL) CSD-DEPRE PRODUCT | | | PWRC |
| 4038 | DP03 | (RAIL) CSD-RTMS-DEPRE PRODUCT | | | PWRC |
| 4039 | DP04 | (RAIL) CSD-RTMS-DEPRE PRODUCT - ASHLAND PETROLEUM CO | | | PWRC |
| 4040 | DP05 | (RAIL) CSD-RTMS-DEPRE PRODUCT | | | PWRC |
| 4041 | DP06 | (RAIL) CSD-WILLIAM GIBB, POSSE-DEPRE PRODUCT | | | PWRC |
| 4042 | DPAF | DEER PARK AUTO FREIGHT | | | SCAC1 |
| 4043 | DPAM | DREW PROPERTY AND MARINE TRANSPORTA | | | SCAC4 |
| 4044 | DPB | Dopravny Podnik Bratislava | City: Bratislava | SK | TRAFFIC |
| 4045 | DPBT | DEPENDABLE TRANSPORT INC | | | SCAC4 |
| 4046 | DPBX | E.I. du Pont de Nemours & Co. | 8/1920 | | NAKINA |
| 4047 | DPBX | E.I. DUPONT DE NEMOURS & CO. | | | PWRC |
| 4048 | DPCA | DIVERSIFIED PLASTICS CORPORATION | | | SCAC4 |
| 4049 | DPCE | DAKOTA PLAINS COOPERATIVE | | | SCAC4 |
| 4050 | DPCH | DWK TRANSPORT | | | SCAC4 |
| 4051 | DPCHJ | Dopravní podnik měst Chomutova a Jirkova | | CZ | TRAFFIC |
| 4052 | DPCL | DAVES PILOT CAR SERVICE | | | SCAC4 |
| 4053 | DPCR | DUNLOP, JAMES TRUCKING | | | SCAC4 |
| 4054 | DPCS | D & P COLLECTIBLES | | | SCAC4 |
| 4055 | DPCT | DOUGLAS PLAINS CATTLE & TRUCKING | | | SCAC4 |
| 4056 | DPCU | DUPONT | | USA | BIC |
| 4057 | DPCU | Dupont | | | RSRV |
| 4058 | DPCU | E.I. DUPONT DE NEMOURS, INC. | | | SCAC3 |
| 4059 | DPCX | Blue Circle, Inc. | added 7/1983; eliminated 10/1988 | | NAKINA |
| 4060 | DPCX | Martin-Marietta Corp. | added 1/1979; 1/1980; eliminated 7/1983 | | NAKINA |
| 4061 | DPCX | Martin-Marietta Cement, Division of Martin-Marietta Corp. | added 10/1972; 1/1975; eliminated 1/1979 | | NAKINA |
| 4062 | DPCX | Dewey Portland Cement Co., Division of Martin-Marletta Corp. | added 7/1962; 7/1965-4/1970; eliminated 10/1972 | | NAKINA |
| 4063 | DPCX | Dewwy Portland Cement Co., Division of American-Marietta Co. | added 7/1960; 4/1961; eliminated 7/1962 | | NAKINA |
| 4064 | DPCX | Dewey Portland Cement Co. | 8/1920-7/1932; 1/1941-10/1957; eliminated 7/1960 | | NAKINA |
| 4065 | DPCX | Dewey Portland Cement Co. | 1/52-10/57; eliminated 7/60 | | NRHS |
| 4066 | DPCX | Dewwy Portland Cement Co., Division of American-Marietta Co. | added 7/60; 4/61 | | NRHS |
| 4067 | DPCX | Dewey Portland Cement Co., Division of Martin-Marletta Corp. | 7/65-4/70; eliminated 10/72 | | NRHS |
| 4068 | DPCX | Martin-Marietta Cement, Division of Martin-Marietta Corp. | added 10/72; 1/75; eliminated 1/79 | | NRHS |
| 4069 | DPCX | Martin-Marietta Corp. | added 1/79; 1/80 | | NRHS |
| 4070 | DPCX | Blue Circle, Inc. | eliminated 10/88 | | NRHS |
| 4071 | DPCX | BLUE CIRCLE INC. [MARTIN-MARIETTA CORP.; DEWEY PORTLAND CEMENT CO.] | | | PWRC |
| 4072 | DPCX | Dewey Portland Cement (Dragon Products) | | | RSRV |
| 4073 | DPCX | Dragon Cement | | USA | TRAFFIC |
| 4074 | DPCZ | DELTECH POLYMERS COMPANY, INC. | | | PWRC |
| 4075 | DPDD | DEPENDABLE TRUCKING EXPEDITED SERVI | | | SCAC4 |
| 4076 | DPDG | DAMPIER & DAUGHTERS | | | SCAC4 |
| 4077 | DPDK | DINKS, P D TRUCKING | | | SCAC4 |
| 4078 | DPDM | DISTRIBUTION P D M 2000 INC | | | SCAC4 |
| 4079 | DPDU | DU PONT DE NEMOURS (NEDERLANDS) BV | | | SCAC4 |
| 4080 | DPDZ | DELAWARE AND HUDSON RAILWAY COMPANY, INC. | | | PWRC |
| 4081 | DPDZ | Delaware and Hudson Railway | | | RSRV |
| 4082 | DPEG | D & P EXPRESS LOGISTICS LLC | | | SCAC4 |
| 4083 | DPEM | DASSELS PETROLEUM INC | | | SCAC4 |
| 4084 | DPEN | DOWLING, PATRICK ENTERPRISES | | | SCAC4 |
| 4085 | DPEO | D'AMICO PETROLEUM INCORPORATED | | | SCAC4 |
| 4086 | DPEP | DOUBLE P EXPRESS | | | SCAC4 |
| 4087 | DPER | DELIVERY PEOPLE, THE | | | SCAC4 |
| 4088 | DPET | DICKERSON PETROLEUM INC | | | SCAC4 |
| 4089 | DPFI | DEER POND FUEL INC | | | SCAC4 |
| 4090 | DPFN | DURUSSELS POTATO FARMS INC | | | SCAC4 |
| 4091 | DPFS | DPF CLEANING SPECIALISTS LIMITED | | | SCAC4 |
| 4092 | DPGE | DEMPSEY | | | SCAC4 |
| 4093 | DPGX | Tractech Systems | 7/2005 (not listed) | | NAKINA |
| 4094 | DPGX | E.I. du Pont de Nemours & Co. | 8/1920 | | NAKINA |
| 4095 | DPGX | *E.I. DUPONT DE NEMOURS & CO. | | | PWRC |
| 4096 | DPGX | +TRACTECH SYSTEMS | | | PWRC |
| 4097 | DPGX | DuPont (Tractech Systems) | | | RSRV |
| 4098 | DPGX | TRACTECH SYSTEMS | | | SCAC4 |
| 4099 | DPH | Domodedovo Airport Handling, CJSC | | RUS | AVCODES |
| 4100 | DPHE | DEPENDABLE HIGHWAY EXPRESS, INC | | | SCAC1 |
