# Relationship history for MSHA mine 4503205

Current hierarchy: **Stremler Virgil → Stremler Gravel → Pangborn 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Stremler Gravel → Pangborn Pit; 1989-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Stremler Virgil → Pangborn Pit; 1989-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Stremler Virgil → Stremler Gravel; 1989-07-01 to current/open; source msha-controller-operator-history