| 4201 | DPT | Libertas Airways | Callsign: Libertas, | HR | AVCODES |
| 4202 | DPTA | DAKOTA PRIDE TRANSPORT | | | SCAC4 |
| 4203 | DPTD | DEPARTED TRANSPORT INC | | | SCAC4 |
| 4204 | DPTE | DIRT POOR TRUCKING LLC | | | SCAC4 |
| 4205 | DPTP | DELTA-P TEST CORP | | | SCAC4 |
| 4206 | DPTS | DE POLI TANKERS BV | | | SCAC4 |
| 4207 | DPTU | TRASPORTI DIPASQUALE SRL | | | SCAC3 |
| 4208 | DPTX | D.P. Tafe | 4/1947-1/1952; eliminated 7/1954 | | NAKINA |
| 4209 | DPTX | E.I. du Pont de Nemours & Co. | 8/1920 | | NAKINA |
| 4210 | DPTX | D.P. Tafe | Jan-52 | | NRHS |
| 4211 | DPTX | *E.I. DUPONT DE NEMOURS & CO. | | | PWRC |
| 4212 | DPTX | *D.P. TAFE | | | PWRC |
| 4213 | DPTY | D & P TRANSPORTATION INC | | | SCAC4 |
| 4214 | DPUS | DUPUIS, STEVEN OIL CO INC | | | SCAC4 |
| 4215 | DPVL | DUPLAINVILLE TRANSPORT INC | | | SCAC4 |
| 4216 | DPWX | Dixon Plywood, a Division of Dixon Lumber Co., Inc. | added 7/1974; 1/1975-1/1980; eliminated 1/1981 | | NAKINA |
| 4217 | DPWX | Dixon Plywood, a Division of Dixon Lumber Co., Inc. | added 7/74; 1/75-1/80; eliminated 1/81 | | NRHS |
| 4218 | DPWX | DIXON PLYWOOD, DIV. DIXON LUMBER CO., INC. | | | PWRC |
| 4219 | DPX | Federal Facilities Corp. | added 10/1954; eliminated 1/1956 | | NAKINA |
| 4220 | DPX | Reconstruction Finance Corp. | 1/1946-7/1954; eliminated 10/1954 | | NAKINA |
| 4221 | DPX | Defense Plant Corp. | 1/1943-1/1945 | | NAKINA |
| 4222 | DPX | Reconstruction Finance Corp. | Jan-52 | | NRHS |
| 4223 | DPX | FEDERAL FACILITIES CORP. [RECONSTRUCTION FINANCE CORP.; DEFENSE PLANT CORP.] | | | PWRC |
| 4224 | DQ | Air Limousin | | F | AVCODES |
| 4225 | DQ | Quikjet Cargo Airlines Pvt. Ltd | | IND | AVCODES |
| 4226 | DQ | Delta Connection Limited | ICAO: DCP, IATA Prefix: 521, Name changed to Air Direct Connect Limited. | EAK | AVCODES |
| 4227 | DQ | Air Europa | ICAO: AEA, | E | AVCODES |
| 4228 | DQ | Coastal Air Transport, Inc. | ICAO: CXT, Callsign: Coastal, IATA Prefix: 457, Designator DQ recalled by IATA | VI | AVCODES |
| 4229 | DQ | Air Direct Connect Limited | IATA Prefix: 521, Name changed from Delta Connection Limited. | EAK | AVCODES |
| 4230 | DQ | Alexandria Airlines | ICAO: KHH, | ET | AVCODES |
| 4231 | DQA | Island Aviation Services Ltd. | IATA: Q2, Callsign: Island Aviation, IATA Prefix: 986, IATA Prefix code reinstated. | MV | AVCODES |
| 4232 | DQA | Island Aviation Services | | | ICAO1 |
| 4233 | DQAV | DAVISON & SONS TRUCKING | | | SCAC4 |
| 4234 | DQE | De Queen and Eastern R.R. Co. | 1/1975-7/2005 | | NAKINA |
| 4235 | DQE | De Queen and Eastern R.R. Co. | 1/75-7/2000 | | NRHS |
| 4236 | DQE | DE QUEEN & EASTERN RAILROAD CO. | | | PWRC |
| 4237 | DQE | De Queen and Eastern Railroad | | | RSRV |
| 4238 | DQI | Cimber Air, Sonderjyllands Flyveselskab | IATA: QI, Callsign: Cimber, IATA Prefix: 647, ICAO designator changed to CIM | DK | AVCODES |
| 4239 | DQLI | DARA LOGISTICS INC | | | SCAC4 |
| 4240 | DQLR | DIRECT LOGISTICS TRANSPORT | | | SCAC4 |
| 4241 | DQMA | DUQUE, MIGUEL ANGEL | | | SCAC4 |
| 4242 | DQMS | DISTRICT MOVING & STORAGE INC | | | SCAC4 |
| 4243 | DR | Mediterranean Air Service | | TN | AVCODES |
| 4244 | DR | Air Link Pty Ltd. | | AUS | AVCODES |
| 4245 | DR | Sociedade Brasileira de Turismo (ROTASTUR) | ICAO: RTR, Callsign: Delta Romeo, ICAO callsign changed to Rotatur | BR | AVCODES |
| 4246 | DR | Avdev Airlines of Australia | | AUS | AVCODES |
| 4247 | DR | Panair Luftverkehrsgesellschaft mbH & Co. | Callsign: Delta Romeo, | D | AVCODES |
| 4248 | DR | Ruili Airlines Co., Ltd. | ICAO: RLH, Callsign: Sendi, Name changed to Sunan Ruili Airlines Co., Ltd. On 18 October 2021. | PRC | AVCODES |
| 4249 | DR | Sunan Ruili Airlines Co., Ltd. | ICAO: RLH, Callsign: Sendi, Name changed from Ruili Airlines Co., Ltd. On 18 October 2021. | PRC | AVCODES |
| 4250 | DR | Dardanelle & Russellville R.R. Co. | 1/1975-1/1980; added 7/1981; eliminated 7/1988; 1/1994-7/2005 | | NAKINA |
| 4251 | DR | Dardanelle & Russellville R.R. Co. | 1/75-1/80; added 7/81; eliminated 7/88; 1/94-7/2000 | | NRHS |
| 4252 | DR | DARDANELLE & RUSSELLVILLE RAILROAD | | | PWRC |
| 4253 | DR | Dardanelle and Russellville Railroad | | | RSRV |
| 4254 | DR | DARDANELLE & RUSSELLVILLE RAILROAD | | | SCAC4 |
| 4255 | DR | Deutsche Reichsbahn (DDR, 1945 - ) | | DDR | TRAFFIC |
| 4256 | DR | Deutsche Regionalbahn | | DE | VKM |
| 4257 | DR&U | Delaware River & Union R.R. | 4/1938 | | NAKINA |
| 4258 | DR&U | Delaware River & Union R.R. Co. (Sun Oil Co.) | 7/1930 | | NAKINA |
| 4259 | DR&U | Delaware River & Union R.R. Co. | 8/1920-7/1923 | | NAKINA |
| 4260 | DR&U | Delaware River & Union R.R. Co. | 23-Jul | | NRHS |
| 4261 | DR&U | Delaware River & Union R.R. | Apr-38 | | NRHS |
| 4262 | DR&U | DELAWARE RIVER & UNION RAILROAD CO. (SUN OIL CO.) | | | PWRC |
| 4263 | DRA | Dravidian Air Services Ltd. | Callsign: Firestone, | GB | AVCODES |
| 4264 | DRA | Dravidian Air Services Ltd. | Callsign: Dravidian, | GB | AVCODES |
| 4265 | DRA | Deer Air Co. Ltd. | | PRC | AVCODES |
| 4266 | DRAA | DUDLEY, R A NURSERIES, INC | | | SCAC4 |
| 4267 | DRAB | DURABOX PAPER INC | | | SCAC4 |
| 4268 | DRABAS | Licencjonowane Przewozy Krajowe i Międzynarodowe Marcin Drabas | | PL | TRAFFIC |
| 4269 | DRAC | DESERT RUNNER TRANSPORTATION INC. | | | SCAC4 |
| 4270 | DRACH | Drachenfelsbahn Königswinter | | D | TRAFFIC |
| 4271 | DRAD | D'EON, R A TRANSPORT LTD | | | SCAC4 |
| 4272 | DRAGA | Drachen-Propan GmbH | | DE | VKM |
| 4273 | DRAK | DRAKE PETROLEUM COMPANY INC | | | SCAC4 |
| 4274 | DRAN | DURAN FREIGHT CORPORATION | | | SCAC4 |
| 4275 | DRAO | DRAGON TRUCKING LTD | | | SCAC4 |
| 4276 | DRAQ | D R A EXPRESS INC | | | SCAC4 |
| 4277 | DRAR | DURAN ARVIZU, JOSE FRANCISCO | | | SCAC4 |
| 4278 | DRAU | DRACONTAINERS CORP | | PA | BIC |
| 4279 | DRAV | DALTON RIGGING & TRANSPORT INC | | | SCAC4 |
| 4280 | DRAX | DRAYCUTT Corp. | added 7/1982; eliminated 1/1990 | | NAKINA |
| 4281 | DRAX | Drake Tank Car Co. | added 1/1966; 10/1966-4/1970; eliminated 11/1973 | | NAKINA |
| 4282 | DRAX | Drake Tank Car Co. | added 1/66; 10/66-4/70; eliminated 11/73 | | NRHS |
| 4283 | DRAX | DRAYCUTT Corp. | added 7/82; eliminated 1/90 | | NRHS |
| 4284 | DRAX | *DRAKE TANK CAR CO. | | | PWRC |
| 4285 | DRAX | *DRAYCUTT CORP. | | | PWRC |
| 4286 | DRAX | DRAYCUTT Corporation | | | RSRV |
| 4287 | DRAY | DRAYCO LOGISTICS LLC | | | SCAC4 |
| 4288 | DRB | Didier Rousset Buy | Callsign: Didier, | RCH | AVCODES |
| 4289 | DRB | Didier Rousset Buy | | | ICAO1 |
| 4290 | DRB | Deutsche Reichsbahn (1937-1945) | Real: DR | D | TRAFFIC |
| 4291 | DRBA | DRIFT EXPLORATION DRILLING | | | SCAC4 |
| 4292 | DRBB | DIAMOND RING SPECIALIZED LLC | | | SCAC4 |
| 4293 | DRBC | D & R TRANSPORTATION | | | SCAC4 |
| 4294 | DRBD | DREYER AND REINBOLD RACING | | | SCAC4 |
| 4295 | DRBE | DART TRANSPORTATION | | | SCAC4 |
| 4296 | DRBJ | DAVIS, RON TRUCKING | | | SCAC4 |
| 4297 | DRBP | DRB TRANSPORT | | | SCAC4 |
| 4298 | DRBR | DRB TRANSPORT INC | | | SCAC4 |
| 4299 | DRC | Triton Airlines, Inc. | Callsign: Triton Air, | CDN | AVCODES |
| 4300 | DRC | Triton Airlines | | | ICAO1 |
