| 1 | SCKX | The Short Creek Coal Co. | 8/1920 | | NAKINA |
| 2 | SCKX | Standard Chlorine Chemical Co. | 1/1943-1/1946 | | NAKINA |
| 3 | SCKX | Spring Creek Coal Co. | added 10/1985; eliminated 10/1986 | | NAKINA |
| 4 | SCKX | Northern Coal Transportation Co. | added 10/1986; 1/1994-7/2005 | | NAKINA |
| 5 | SCKX | Spring Creek Coal Co. | eliminated 10/86 | | NRHS |
| 6 | SCKX | Northern Coal Transportation Co. | added 10/86; 1/94-7/2000 | | NRHS |
| 7 | SCKX | *SHORT CREEK COAL CO. | | | PWRC |
| 8 | SCKX | *STANDARD CHLORINE CHEMICAL CO. | | | PWRC |
| 9 | SCKX | +NORTHERN COAL TRANSPORTATION CO. [SPRING CREEK COAL CO.] | | | PWRC |
| 10 | SCKX | Northern Coal Transportation | | | RSRV |
| 11 | SCKX | NORTHERN COAL TRANSPORTATION CO. | | | SCAC4 |