| 1 | HSW | Aerocombi, S.A. | Callsign: Iberswiss, | E | AVCODES |
| 2 | HSW | Helena Southwestern R.R. Co. | 1/1975; eliminated 10/1976; added 7/1979; 1/1980; eliminated 1/1989; eliminated 4/1989 | | NAKINA |
| 3 | HSW | Helena Southwestern R.R. Co. | 1/75; added 7/79; 1/80; eliminated 1/89; eliminated 4/89 | | NRHS |
| 4 | HSW | Historischer Schienenverkehr Wesel e.V. | Wesel | D | privat-bahn.de |
| 5 | HSW | HELENA SOUTHWESTERN RAILROAD | | | PWRC |
| 6 | HSW | Helena Southwestern Railroad | | | RSRV |
| 7 | HSW | Historischer Schienenverkehr Wesel e.V. | | DE | VKM |
| 8 | HSWK | HORNSCREW TRUCKING | | | SCAC4 |
| 9 | HSWS | HIGH SIERRA TRANSPORTATION LLC | | | SCAC4 |
| 10 | HSWX | Min-Ad, Inc. | 4/1970; added 7/1970; eliminated 10/1970 | | NAKINA |
| 11 | HSWX | Hercules Petroleum Co. | 8/1920 | | NAKINA |
| 12 | HSWX | Min-Ad, Inc. | 4/70; added 7/70; eliminated 10/70 | | NRHS |
| 13 | HSWX | *HERCULES PETROLEUM CO. | | | PWRC |
| 14 | HSWX | *MIN-AD, INC. | | | PWRC |
