# Relationship history for MSHA mine 3301625

Current hierarchy: **Oster Enterprises Inc → Oster Sand & Gravel → Oster Sand & Gravel-Massillon Plant**

- 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:** Oster Sand & Gravel → Oster Sand & Gravel-Massillon Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Oster Enterprises Inc → Oster Sand & Gravel-Massillon Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Oster Enterprises Inc → Oster Sand & Gravel; 1950-01-01 to current/open; source msha-controller-operator-history