# Relationship history for MSHA mine 4503023

Current hierarchy: **Pierce County-WA → Pierce County River Improvement → Weyerhaeuser Rock 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:** Pierce County-WA → Weyerhaeuser Rock Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Pierce County River Improvement → Weyerhaeuser Rock Quarry; 1984-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Pierce County-WA → Pierce County River Improvement; 1984-08-01 to current/open; source msha-controller-operator-history