| 1 | ROCX | Rocky Mountain Transportation Services | added 7/1995; 7/2000-7/2005 | | NAKINA |
| 2 | ROCX | Rock Island Improvement Co. | added 1/1979; 1/1980; eliminated 7/1980 | | NAKINA |
| 3 | ROCX | Rock Island Improvement Co. | added 1/79; 1/80; eliminated 7/80 | | NRHS |
| 4 | ROCX | Rocky Mountain Transportation Services | added 7/95; 7/2000 | | NRHS |
| 5 | ROCX | *ROCK ISLAND IMPROVEMENT COMPANY (ROCK ISLAND) | | | PWRC |
| 6 | ROCX | +ROCKY MOUNTAIN TRANSPORTATION SERVICES | | | PWRC |
| 7 | ROCX | Rock Island Improvement (Rocky Mountain Transportation Services) | | | RSRV |
| 8 | ROCX | ROCKY MOUNTAIN TRANSPORTATIN SERVIC | | | SCAC4 |
