# Relationship history for MSHA mine 4503421

Current hierarchy: **John  Schilaty → Nw Sand & Gravel Products Inc → NW Sand & Gravel Inc**

- 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:** Nw Sand & Gravel Products Inc → NW Sand & Gravel Inc; 2000-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John  Schilaty → NW Sand & Gravel Inc; 2000-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John  Schilaty → Nw Sand & Gravel Products Inc; 2000-02-01 to current/open; source msha-controller-operator-history