# Relationship history for MSHA mine 4402375

Current hierarchy: **Roy D  Simmons Jr → Quality Sand & Gravel → Quality Sand & Gravel**

- 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:** Quality Sand & Gravel Inc → Quality Sand & Gravel; 1950-01-01 to 1984-05-22; source msha-controller-operator-history
- **controller_controls_mine:** Boyd Kenneth B → Quality Sand & Gravel; 1950-01-01 to 1984-05-22; source msha-controller-operator-history
- **controller_controls_operator:** Boyd Kenneth B → Quality Sand & Gravel Inc; 1950-01-01 to 1984-05-22; source msha-controller-operator-history
- **operator_operates_mine:** Quality Sand & Gravel → Quality Sand & Gravel; 1984-05-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Roy D  Simmons Jr → Quality Sand & Gravel; 1984-05-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Roy D  Simmons Jr → Quality Sand & Gravel; 1984-05-23 to current/open; source msha-controller-operator-history