# Relationship history for MSHA mine 4800559

Current hierarchy: **N A Degerstrom → N A Degerstrom Inc → Split Rock Project**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Western Nuclear Inc → Split Rock Project; 1950-01-01 to 1994-12-28; source msha-controller-operator-history
- **controller_controls_mine:** Phelps Dodge Corp → Split Rock Project; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Phelps Dodge Corp → Western Nuclear Inc; 1950-01-01 to 1994-12-28; source msha-controller-operator-history
- **controller_controls_mine:** N A Degerstrom → Split Rock Project; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** N A Degerstrom Inc → Split Rock Project; 1994-12-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** N A Degerstrom → N A Degerstrom Inc; 1994-12-29 to current/open; source msha-controller-operator-history