# Relationship history for MSHA mine 4102975

Current hierarchy: **John R  Thompson → J R Thompson Inc → Campbell 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** J R Thompson Inc → Campbell Quarry; 1980-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John R  Thompson → Campbell Quarry; 1980-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John R  Thompson → J R Thompson Inc; 1980-01-01 to current/open; source msha-controller-operator-history