| 1 | HRD | Marshall University Bill Noe Flight School | Callsign: Marshall Herd, | USA | AVCODES |
| 2 | HRDD | HARTS RAPID DELIVERY | | | SCAC4 |
| 3 | HRDE | H R DENTAL PRODUCTS INC | | | SCAC4 |
| 4 | HRDF | HOT ROD TRUCKING SERVICES INC | | | SCAC4 |
| 5 | HRDH | HAMMER, D TRUCKING INC | | | SCAC4 |
| 6 | HRDK | HORD TRUCKING INC | | | SCAC4 |
| 7 | HRDL | Hudson River Day Line | 1/1975-1/1980 | | NAKINA |
| 8 | HRDL | Hudson River Day Line | 1/75-1/80 | | NRHS |
| 9 | HRDL | HUDSON RIVER DAY LINE | | | PWRC |
| 10 | HRDL | Hudson River Day Line | | | RSRV |
| 11 | HRDM | HARDING METALS INC | | | SCAC4 |
| 12 | HRDN | HARDIN TRUCKING INC | | | SCAC4 |
| 13 | HRDR | HARRIS DISTRIBUTING COMPANY | | | SCAC4 |
| 14 | HRDV | HERNANDEZ RIVAS, JULIAN ALONSO | | | SCAC4 |
| 15 | HRDX | Silver Star Enterprises, Inc. | added 1/1994; 7/2000; eliminated 7/2004; 7/2005 (not listed) | | NAKINA |
| 16 | HRDX | M-P Petroleum Ltd. | added 10/1975; eliminated 10/1978 | | NAKINA |
| 17 | HRDX | Hagaman Refining Co. | 8/1920 | | NAKINA |
| 18 | HRDX | Hydrocarbons Inc. | added 10/1974; 1/1975; eliminated 10/1975 | | NAKINA |
| 19 | HRDX | Hydrocarbons Inc. | added 10/74; 1/75 | | NRHS |
| 20 | HRDX | M-P Petroleum Ltd. | eliminated 10/78 | | NRHS |
| 21 | HRDX | Silver Star Enterprises, Inc. | added 1/94; 7/2000 | | NRHS |
| 22 | HRDX | *HAGAMAN REFINING CO. | | | PWRC |
| 23 | HRDX | *M-P PETROLEUM LTD. [HYDROCARBONS, INC.] | | | PWRC |
| 24 | HRDX | +SILVER STAR ENTERPRISES, INC. | | | PWRC |
| 25 | HRDX | Hagaman Refining (Silver Star Enterprises) | | | RSRV |
