# Relationship history for MSHA mine 4501993

Current hierarchy: **Thurston County - Wa → Thurston County Road Department → Steilacoom Road Pit**

- 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:** Thurston County Road Department → Steilacoom Road Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Thurston County - Wa → Steilacoom Road Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thurston County - Wa → Thurston County Road Department; 1950-01-01 to current/open; source msha-controller-operator-history