# Relationship history for MSHA mine 4503224

Current hierarchy: **Harry W  Hart → Washington Rock Quarries, Inc. → Kapowsin 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

- **operator_operates_mine:** Washington Rock Quarries, Inc. → Kapowsin Quarry; 1990-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Harry W  Hart et al → Kapowsin Quarry; 1990-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harry W  Hart et al → Washington Rock Quarries, Inc.; 1990-04-01 to current/open; source msha-controller-operator-history