# Relationship history for MSHA mine 4500868

Current hierarchy: **Whitman County - Wa → Whitman County Engineers → Union Center Quarry**

- 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

- **controller_controls_mine:** N A Degerstrom → Union Center Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Whitman County Engineers → Union Center Quarry; 1950-01-01 to 1979-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Whitman County - Wa → Union Center Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Whitman County - Wa → Whitman County Engineers; 1950-01-01 to 1979-09-30; source msha-controller-operator-history
- **operator_operates_mine:** N A Degerstrom Inc → Union Center Quarry; 1979-10-01 to 1980-09-30; source msha-controller-operator-history
- **controller_controls_operator:** N A Degerstrom → N A Degerstrom Inc; 1979-10-01 to 1980-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Whitman County Engineers → Union Center Quarry; 1980-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Whitman County - Wa → Whitman County Engineers; 1980-10-01 to current/open; source msha-controller-operator-history