| 3801 | OTR | OAKLAND TERMINAL RLWY | | | PWRC |
| 3802 | OTR | Oakland Terminal Railway | | | RSRV |
| 3803 | OTRA | ONE ONE THREE EIGHT NINE TWO THREE | | | SCAC4 |
| 3804 | OTRB | ORTIZ TRANSPORTATION SERVICES LLC | | | SCAC4 |
| 3805 | OTRC | OVERSEAS TRANSPORTATION CO | | | PWRC |
| 3806 | OTRC | OTR RECYCLING | | | SCAC4 |
| 3807 | OTRD | OVER THE ROAD TRUCKING INC | | | SCAC3 |
| 3808 | OTRD | ON THE ROCKS ENTERPRISES INC | | | SCAC4 |
| 3809 | OTRE | O T R EXPRESS INC | | | SCAC3 |
| 3810 | OTRE | OTR LOGISTICS INC | | | SCAC4 |
| 3811 | OTRF | OTTO TRANSFER INC | | | SCAC4 |
| 3812 | OTRG | OUTBOUND TRUCKING INC | | | SCAC3 |
| 3813 | OTRG | OLIVER, T R TRUCKING INC | | | SCAC4 |
| 3814 | OTRI | ORANGEVILLE TRAILERS | | | SCAC4 |
| 3815 | OTRK | OTRA TRUCKING | | | SCAC3 |
| 3816 | OTRL | ON-TRUX LTD | | | SCAC4 |
| 3817 | OTRN | ORTRAN INCORPORATED | | | SCAC4 |
| 3818 | OTRO | ONE THREE FOUR NINE ONE SIX FIVE (1 | | | SCAC4 |
| 3819 | OTRR | OVER THE ROAD SERVICES INC | | | SCAC3 |
| 3820 | OTRR | OAKRIDGE TRANSPORT | | | SCAC4 |
| 3821 | OTRS | OMNI TRANSERVE | | | SCAC3 |
| 3822 | OTRV | OTR REPAIR SERVICE | | | SCAC3 |
| 3823 | OTRV | OVER THE ROAD LOGISTICS | | | SCAC4 |
| 3824 | OTRX | On-Track Railway Services Ltd. | 7/2000-7/2005 (not listed) | | NAKINA |
| 3825 | OTRX | On-Track Railway Services Ltd. | Jul-00 | | NRHS |
| 3826 | OTRX | ON-TRACK RAILWAY SERVICES LIMITED | | | PWRC |
| 3827 | OTRX | On-Track Railway Services | | | RSRV |
| 3828 | OTRX | ON-TRACK RAILWAY SERVICES LTD | | | SCAC4 |
| 3829 | OTRY | OTTERY TRANSPORTATION INC | | | SCAC4 |
| 3830 | OTS | Société de Taxis Aériens (SOTA) | Callsign: Sota, | RMM | AVCODES |
| 3831 | OTS | Aerotresalia, S.A. de C.V. | Callsign: Tresalia, | MEX | AVCODES |
| 3832 | OTS | Osaka Port Transport System | | J | TRAFFIC |
| 3833 | OTS | OTS Omnia Trasporti Speciali SRL | | IT | VKM |
| 3834 | OTSB | O T S ASTRACON LLC | | | SCAC4 |
| 3835 | OTSC | OGDEN TRANSFER AND STORAGE COMPANY | | | SCAC3 |
| 3836 | OTSC | ONLINE TRUCKING SERVICE CO | | | SCAC4 |
| 3837 | OTSD | OLYMPIC TRANSPORTATION SERVICES INC | | | SCAC4 |
| 3838 | OTSG | OAK TRANSPORTATION SERVICES LLC | | | SCAC4 |
| 3839 | OTSH | OT SHIPPING AB | | | SCAC3 |
| 3840 | OTSI | ORANGE TRANSPORTATION SERVICES INC | | | SCAC3 |
| 3841 | OTSL | OVERLOAD TRACTOR SERVICE LTD | | | SCAC3 |
| 3842 | OTSM | ONTARIO SCRAP METAL INC | | | SCAC3 |
| 3843 | OTSN | ORIENT TARGET SHIPPING COMPANY LIMI | | | SCAC4 |
| 3844 | OTSO | ONE TWO SIX TWO THREE EIGHT SIX (12 | | | SCAC4 |
| 3845 | OTSON | Oiltanking Sonmarin Oy | | FI | VKM |
| 3846 | OTSP | OCEAN TRANSPORTATION SERVICES | | | SCAC3 |
| 3847 | OTSR | OLYMPIC AIRFREIGHT TRANSPORTATION | | | SCAC4 |
| 3848 | OTSS | O T S SPA | | | SCAC4 |
| 3849 | OTST | OWENS, T W & SONS TRUCKING INC | | | SCAC3 |
| 3850 | OTST | ONE TWO SEVEN ONE ONE FOUR TWO (127 | | | SCAC4 |
| 3851 | OTSU | OTSUKA CHEMICAL CO LTD | | | SCAC4 |
| 3852 | OTSV | OTTOS SERVICENTER | | | SCAC3 |
| 3853 | OTSX | On-Track Rail Services, LLC | 7/2000-7/2005 (not listed) | | NAKINA |
| 3854 | OTSX | On-Track Rail Services, LLC | Jul-00 | | NRHS |
| 3855 | OTSX | ON-TRACK RAILWAY SERVICES LIMITED | | | PWRC |
| 3856 | OTSX | On-Track Railway Services | | | RSRV |
| 3857 | OTSX | ON TRACK RAIL SERVICES LLC | | | SCAC4 |
| 3858 | OTT | OTT Airlines Co., Ltd. | IATA: JF, Callsign: OTT Airlines, Subsidiary of China Eastern Airlines. Planned to operate Comac C919 and ARJ21. | PRC | AVCODES |
| 3859 | OTT | Ottumwa Terminal R.R. Co. | added 1/1988; eliminated 7/1990; 1/1994-7/2005 | | NAKINA |
| 3860 | OTT | Ottumwa Terminal R.R. Co. | added 1/88; eliminated 7/90; 1/94-7/2000 | | NRHS |
| 3861 | OTT | OTTUMWA TERMINAL RAILROAD COMPANY | | | PWRC |
| 3862 | OTT | Ottumwa Terminal Railroad | | | RSRV |
| 3863 | OTT | OTTUMWA TERMINAL RAILROAD CO | | | SCAC4 |
| 3864 | OTT1 | TEST CARRIER | | | SCAC3 |
| 3865 | OTTA | OTT TRUCKING INC | | | SCAC4 |
| 3866 | OTTC | OCEAN TRAILER TRANSPORT | | | PWRC |
| 3867 | OTTC | OTTO CANDIES LLC | | | SCAC4 |
| 3868 | OTTD | OTTO, J W DRAYAGE | | | SCAC3 |
| 3869 | OTTD | ONE TWO THREE (123) DELIVERY INC | | | SCAC4 |
| 3870 | OTTE | OTTE, CLYDE W | | | SCAC3 |
| 3871 | OTTF | ON TIME TRUCKING INC | | | SCAC4 |
| 3872 | OTTG | OTT TRUCKING | | | SCAC3 |
| 3873 | OTTH | ONE THREE THREE TWO SIX EIGHT EIGHT | | | SCAC4 |
| 3874 | OTTI | O T P TRANSPORT INC | | | SCAC4 |
| 3875 | OTTJ | OTT, JIM TRUCKING INC | | | SCAC3 |
| 3876 | OTTK | OTT, TED TRUCKING | | | SCAC3 |
| 3877 | OTTK | ORTEGA TRUCKING | | | SCAC4 |
| 3878 | OTTL | OTTEN TRUCK LINE | | | SCAC3 |
| 3879 | OTTM | ON TIME TRUCKERS INC | | | SCAC4 |
| 3880 | OTTN | ONE TWO THREE (123) TRANSPORT INC | | | SCAC4 |
| 3881 | OTTO | OTTO | | | SCAC3 |
| 3882 | OTTO | ONE THREE THREE FOUR ONE NINE FOUR | | | SCAC4 |
| 3883 | OTTO | Technischer Handel Otto Rentschler | | DE | VKM |
| 3884 | OTTP | OTT PLASTICS EXPRESS INC | | | SCAC3 |
| 3885 | OTTQ | OTT, LAVERNE E INC | | | SCAC3 |
| 3886 | OTTQ | OTTO TRANSPORTATION LLC | | | SCAC4 |
| 3887 | OTTR | OTT, ROLAND | | | SCAC3 |
| 3888 | OTTS | O T T TRANSPORTATION SERVICE | | | SCAC3 |
| 3889 | OTTS | ONE THREE THREE SEVEN ZERO THREE (1 | | | SCAC4 |
| 3890 | OTTT | OTTAWA TRAVEL CENTENNIAL TOWERS | | | SCAC3 |
| 3891 | OTTU | OTTEVANGER MILLING ENGINEERS | | NL | BIC |
| 3892 | OTTW | OTTAWAY MOTOR EXPRESS | | | SCAC3 |
| 3893 | OTTW | OTTAWAY MOTOR EXPRESS LTD | | | SCAC4 |
| 3894 | OTTX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 3895 | OTTX | Trailer Train Co. | 7/1965 (not listed); added 10/1965; 10/1968-1/1980; eliminated 1/1992 | | NAKINA |
| 3896 | OTTX | Trailer Train Co. | 7/1965; added 10/1965; 10/1966 | | NAKINA |
| 3897 | OTTX | Trailer Train Co. (FMS flats specially equipped to provide for loading of agricultural equipment) | 10/1968 | | NAKINA |
| 3898 | OTTX | Trailer Train Co. (flat cars equipped with 64 chains, with snubbers, each secured to movable and retractable tie-down winches in 4 longitudinal channels, for transporting agricultural equipment) | 4/1970-1/1980 | | NAKINA |
| 3899 | OTTX | Trailer Train Co./TTX Co. (flat cars equipped with 48 chains, with snubbers, each secured to movable and retractable tie-down winches in 4 longitudinal channels; for transporting agricultural equipment) | 7/1985-1/1994 | | NAKINA |
| 3900 | OTTX | TTX Co. (flat cars equipped with 48 chains, with snubbers, each secured to movable and retractable tie-down winches in 4 longitudinal channels; for transporting agricultural equipment, equipped with end of car cush.) | 7/2000 | | NAKINA |
