| 1 | CUS | Cronus Airlines | IATA: X5, Callsign: Cronus, IATA designator X5 recalled due merger with Aegean Airlines S.A. A3/AEE | GR | AVCODES |
| 2 | CUS | CHICAGO UNION STATION CO [now AMTRAK] | | | PWRC |
| 3 | CUSA | Coach USA | | USA | TRAFFIC |
| 4 | CUSC | CUSTOM CARRIER SERVICE | | | SCAC4 |
| 5 | CUSD | CUSTOM DELIVERIES | | | SCAC3 |
| 6 | CUSE | CLOUSE TRUCKING INC | | | SCAC3 |
| 7 | CUSE | CUSTINO ENTERPRISES | | | SCAC4 |
| 8 | CUSF | CUSTOM REFRIGERATED CARRIERS INC | | | SCAC3 |
| 9 | CUSF | CUSTOM SURFACE TRANSPORT INC | | | SCAC4 |
| 10 | CUSG | CUSHING TRUCKING, INC | | | SCAC3 |
| 11 | CUSH | CURTIS, STEPHEN A | | | SCAC4 |
| 12 | CUSI | CONTI USA INC | | | SCAC3 |
| 13 | CUSI | CONTI USA INC | | | SCAC4 |
| 14 | CUSJ | CURTIS, JOSEPH H & SONS | | | SCAC3 |
| 15 | CUSJ | CUSUMANO & SONS INC | | | SCAC4 |
| 16 | CUSK | CUSICK, JAMES CO | | | SCAC3 |
| 17 | CUSK | CUSTOM CARRIER INC | | | SCAC4 |
| 18 | CUSL | CUTRER, SAM L TRUCKING INC | | | SCAC3 |
| 19 | CUSN | CURTIS, NEAL | | | SCAC3 |
| 20 | CUSO | COUSINS METAL INDUSTRIES INC | | | SCAC3 |
| 21 | CUSO | COUSINS METAL INDUSTRIES INC | | | SCAC4 |
| 22 | CUSP | CURLY STANDARD PLACE | | | SCAC4 |
| 23 | CUSQ | CURTOS TRANSFER & STORAGE | | | SCAC3 |
| 24 | CUSQ | CUSTOMIZED TRANSPORTATION SERVICE I | | | SCAC4 |
| 25 | CUSR | CUSTOMER SERVICES INC | | | SCAC3 |
| 26 | CUSR | CUSTOM TRUCKING INC | | | SCAC4 |
| 27 | CUSS | CUSTOM STEEL LTD | | | SCAC4 |
| 28 | CUST | Chicago Union Station Co. | 1/1975-7/2005 | | NAKINA |
| 29 | CUST | Chicago Union Station Co. | 1/75-7/2000 | | NRHS |
| 30 | CUST | CHICAGO UNION STATION CO [NOW AMTRAK] | | | PWRC |
| 31 | CUST | Chicago Union Station | | | RSRV |
| 32 | CUST | CDT USA INC | | | SCAC4 |
| 33 | CUSV | CUSTOM TOWING INC | | | SCAC3 |
| 34 | CUSV | CUSTOMEX | | | SCAC4 |
| 35 | CUSW | CUSTOM LOADING | | | SCAC4 |
| 36 | CUSX | E.L. Bride Co. | added 1/1973; eliminated 1/1975 | | NAKINA |
| 37 | CUSX | Custom Car Service Corp. | added 7/1959; 4/1961-4/1970; eliminated 1/1973 | | NAKINA |
| 38 | CUSX | Custom Car Service Corp. | added 7/59; 4/61-4/70 | | NRHS |
| 39 | CUSX | E.L. Bride Co. | eliminated 1/75 | | NRHS |
| 40 | CUSX | E. L. BRIDE CO. [CUSTOM CAR SERVICE CO.] | | | PWRC |
| 41 | CUSX | CUSTOM CAR SERVICE CORP | | | SCAC3 |
| 42 | CUSZ | CITY UTILITIES OF SPRINGFIELD | | | PWRC |
