# Relationship history for MSHA mine 4500956

Current hierarchy: **John  Van Boven → Van Boven Gravel Company → Nooksack River Gravel Bar**

- 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:** Van Boven Gravel Company → Nooksack River Gravel Bar; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** John  Van Boven → Nooksack River Gravel Bar; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** John  Van Boven → Van Boven Gravel Company; 1950-01-01 to current/open; source msha-controller-operator-history