| 12301 | COMP | COMPTON, T H, INC | | | SCAC3 |
| 12302 | COMS | COMMERCIAL FURNITURE DISTRIBUTORS I | | | SCAC3 |
| 12303 | COMS | CONTRACT FURNITURE TRANSPORT INC | | | SCAC4 |
| 12304 | COMSA | | | E | TRAFFIC |
| 12305 | COMTRANSIT | Community Transit | | USA | TRAFFIC |
| 12306 | COMU | COMMONWEALTH STEEL COMPANY PTY LTD | | AUS | BIC |
| 12307 | COMU | COMPREHENSIVE SHIPPING LTD | | | SCAC3 |
| 12308 | COMU | COMMONWEA | | | SCAC4 |
| 12309 | COMW | COLE MOVING & STORAGE COMPANY INC | | | SCAC3 |
| 12310 | COMW | COLUMBIA MACHINE WORKS LTD | | | SCAC4 |
| 12311 | COMX | Exelon Generation Co., LLC | added 10/2006 | | NAKINA |
| 12312 | COMX | Commonwealth Edison Co. | added 4/1995; 7/2000-7/2005; eliminated 10/2006 | | NAKINA |
| 12313 | COMX | Commerce Transportation System (North American Car Co.) | 7/1923 | | NAKINA |
| 12314 | COMX | Commerce Transportation System | 8/1920 | | NAKINA |
| 12315 | COMX | Commonwealth Edison Co. | added 4/95; 7/2000 | | NRHS |
| 12316 | COMX | *COMMERCE TRANSPORTATION SYSTEM (NORTH AMERICAN CAR CO.) | | | PWRC |
| 12317 | COMX | +EXELON GENERATION CO. LLC [COMMONWEALTH EDISON CO.] | | | PWRC |
| 12318 | COMX | Commonwealth Edison | | | RSRV |
| 12319 | COMX | EXELON GENERATING COMPANY LLC | | | SCAC4 |
| 12320 | COMY | COLORADO MOVERS INC | | | SCAC3 |
| 12321 | COMZ | CORDERO MINE | | | PWRC |
| 12322 | CON | Continental Oil Co. | Callsign: Conoco, Name changed to ConcoPhillips Co. | USA | AVCODES |
| 12323 | CON | ConocoPhillips Co. | Callsign: Conoco, Name changed from Continental Oil Co. | USA | AVCODES |
| 12324 | CON | Continental Oil | | | ICAO1 |
| 12325 | CON | | | USA | TRAFFIC |
| 12326 | CONA | CONTINENTAL AIRLINES | | | PWRC |
| 12327 | CONA | CONTINENTAL AIRLINES (AIR CODE CO) | | | SCAC4 |
| 12328 | CONC | CONSOLIDATION COAL COMPANY | | | PWRC |
| 12329 | CONC | CONCRETE DELIVERY CO INC | | | SCAC3 |
| 12330 | COND | CONDRA TRANSPORTATION LTD | | | SCAC3 |
| 12331 | COND | COONEN INC | | | SCAC4 |
| 12332 | COND | Condor Flugdienst GmbH | Real: CFG | D | TRAFFIC |
| 12333 | CONE | CENTURY ONE TRANSPORT INC | | | SCAC4 |
| 12334 | CONF | CONNER TRUCK LINE | | | SCAC3 |
| 12335 | CONF | CONNER TRUCK LINE | | | SCAC4 |
| 12336 | CONF | | | | TRAFFIC |
| 12337 | CONG | CLARKSVILLE OIL & GAS COMPANY | | | SCAC4 |
| 12338 | CONH | CONGDON MOVING AND STORAGE COMPANY | | | SCAC3 |
| 12339 | CONI | CONEX INTERNATIONAL | | | SCAC4 |
| 12340 | CONL | CONLON, JOE TRUCKING | | | SCAC4 |
| 12341 | CONM | CONROTTO MIKE TRUCKING | | | SCAC3 |
| 12342 | CONN | CON-TRAND SERVICES INC | | | SCAC3 |
| 12343 | CONN | CON-TRAND SERVICES INC | | | SCAC4 |
| 12344 | CONP | CONSTRUCTORA Y PERFORADORA LATINA | | | SCAC4 |
| 12345 | CONQ | CONNECTION COMPANY | | | SCAC3 |
| 12346 | CONR | COC TRANSPORT INCORPORATED | | | SCAC4 |
| 12347 | CONS | CONSOLIDATED CARRIERS CORP | | | SCAC3 |
| 12348 | CONS | CONSOLIDATED CARRIERS CORP | | | SCAC4 |
| 12349 | CONS | Regia Autonoma de Transport in Constanta | Real: RATC, City: Constanta | RO | TRAFFIC |
| 12350 | CONSA | Constellium Valais SA | | CH | VKM |
| 12351 | CONT | (INTU) INTERPOOL HYBRID JCTS AND TR65/67 | | | PWRC |
| 12352 | CONT | CONTERM | | | SCAC3 |
| 12353 | CONT | CONTRANS GMBH | | | SCAC4 |
| 12354 | CONT | Continental | | | TRAFFIC |
| 12355 | CONTC | Contec Rail Aps | | DK | VKM |
| 12356 | Contec | Contec Rail ApS | 2007 - | DK | jernbanen.dk |
| 12357 | CONTEC | Contec Rail ApS | 2007 | DK | TRAFFIC |
| 12358 | CONTI | Continental Rail | | E | TRAFFIC |
| 12359 | CONU | CONTAINER OF AMERICA LLC | | USA | BIC |
| 12360 | CONU | CONTRANS | | | PWRC |
| 12361 | CONU | Contrans | | | RSRV |
| 12362 | CONU | CONTRANS | | | SCAC3 |
| 12363 | CONU | CONTRANS LEASING VERWALTUNGS GMBH | | | SCAC4 |
| 12364 | CONV | CONTINENTAL VANGUARD INC | | | SCAC3 |
| 12365 | CONVE | CONVEY, a.s. | | SK | VKM |
| 12366 | CONW | CONWAY SCENIC RAILROAD | | | PWRC |
| 12367 | CONW | CONTI-OSG ASSOCIATES (IV) C.V. | | | SCAC3 |
| 12368 | CONX | ConocoPhillips Co. | added 10/2003; 7/2005 | | NAKINA |
| 12369 | CONX | Conoco Inc. | added 1/1980; 1/1980-7/2000; eliminated 10/2003 | | NAKINA |
| 12370 | CONX | Continental Oil Co. | 7/1930-1/1975; eliminated 1/1980 | | NAKINA |
| 12371 | CONX | Continental Oil Co. | 4/38-1/75; eliminated 1/80 | | NRHS |
| 12372 | CONX | Conoco Inc. | added 1/80; 1/80-7/2000 | | NRHS |
| 12373 | CONX | CONOCO PHILLIPS CO. [CONOCO INC.; CONTINENTAL OIL CO.] | | | PWRC |
| 12374 | CONX | Conoco Inc. | | | RSRV |
| 12375 | CONX | CONOCO INC (RAIL CARS) | | | SCAC3 |
| 12376 | CONX | CONOCOPHILLIPS COMPANY | | | SCAC4 |
| 12377 | CONY | CONTINENTAL DRIVEAWAY INC | | | SCAC3 |
| 12378 | COO | Corporate Airlink | Callsign: Corporate, | CDN | AVCODES |
| 12379 | COO | Cove Aviation Partners, LLC | Callsign: Cove, | USA | AVCODES |
| 12380 | COO | Corporate Airlink | | | ICAO1 |
| 12381 | COOA | CO-OPERATIVE TOURS | | | SCAC3 |
| 12382 | COOA | CHOOPA LLC | | | SCAC4 |
| 12383 | COOB | COOMES INC | | | SCAC3 |
| 12384 | COOB | COOPER, JACK TRANSPORT COMPANY INC | | | SCAC4 |
| 12385 | COOC | COOK TRANSPORT | | | SCAC3 |
| 12386 | COOC | COCHRAN OIL COMPANY INCORPORATED | | | SCAC4 |
| 12387 | COOD | CONSOLIDATED CARRIERS INC | | | SCAC3 |
| 12388 | COOD | COORS DISTRIBUTING COMPANY OF NORTH | | | SCAC4 |
| 12389 | COOE | COOKE MOTOR EXPRESS | | | SCAC3 |
| 12390 | COOE | COOMES INC | | | SCAC4 |
| 12391 | COOF | CO-OPERATIVE FEED DEALERS INC | | | SCAC4 |
| 12392 | COOG | CORTRANS LOGISTICS LLC | | | SCAC4 |
| 12393 | COOH | COOK MOTOR LINES INC | | | SCAC3 |
| 12394 | COOI | CO-OP TRANSPORTATION | | | SCAC3 |
| 12395 | COOJ | COOPER, JACK TRANSPORT COMPANY INC | | | SCAC3 |
| 12396 | COOJ | COOPER, JACK TRANSPORT COMPANY INC | | | SCAC4 |
| 12397 | COOK | Cook Transit | 1/1994-7/2005 | | NAKINA |
| 12398 | COOK | Cook Transit | 1/94-7/2000 | | NRHS |
| 12399 | COOK | COOK TRANSIT | | | PWRC |
| 12400 | COOK | Cook Transit | | | RSRV |
