| 1 | UNPX | Union Petroleum Co. | 8/1920-7/1923 | | NAKINA |
| 2 | UNPX | Union Petroleum Co. (Sinclair Refining Co.) | 7/1930-7/1935 | | NAKINA |
| 3 | UNPX | Sinclair Refining Co. | 7/1937-7/1954; eliminated 1/1958 | | NAKINA |
| 4 | UNPX | Union Tank Car Co. | 10/1957; added 1/1958; 4/1961; added 7/1964; 7/1965-10/1966; added 1/1970; 4/1970; eliminated 1/1974 | | NAKINA |
| 5 | UNPX | Procor Ltd. | added 1/1974; 1/1975-7/2005 | | NAKINA |
| 6 | UNPX | Union Petroleum Co. (Sinclair Refining Co.) | Apr-38 | | NRHS |
| 7 | UNPX | Sinclair Refining Co. | 1/52; eliminated 1/58 | | NRHS |
| 8 | UNPX | Union Tank Car Co. | 10/57; added 1/58; 4/61; added 7/64; 7/65-10/66; added 1/70; 4/70; eliminated 1/74 | | NRHS |
| 9 | UNPX | Procor Ltd. | added 1/74; 1/75-7/2000 | | NRHS |
| 10 | UNPX | (PROX) PROCOR LIMITED [UNION TANK CAR CO.; SINCLAIR REFINING CO.; UNION PETROLEUM CO.] | | | PWRC |
| 11 | UNPX | Union Petroleum (Procor) | | | RSRV |
| 12 | UNPX | PROCOR LIMITED | | | SCAC4 |
| 13 | UNPX | Procor Ltd. | | USA | TRAFFIC |
