# Relationship history for MSHA mine 2501172

Current hierarchy: **Michael D  Quinn → Quinn Sand & Gravel → Quinn Sand & Gravel Dredge #1**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Quinn Sand & Gravel → Quinn Sand & Gravel Dredge #1; 1997-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Michael D  Quinn → Quinn Sand & Gravel Dredge #1; 1997-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael D  Quinn → Quinn Sand & Gravel; 1997-05-01 to current/open; source msha-controller-operator-history