# Relationship history for MSHA mine 2300678

Current hierarchy: **Herbert F  Boettcher → Boettcher Concrete Company → BOETTCHER SAND & GRAVEL 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:** Boettcher Concrete Company → BOETTCHER SAND & GRAVEL PLANT; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Herbert F  Boettcher → BOETTCHER SAND & GRAVEL PLANT; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Herbert F  Boettcher → Boettcher Concrete Company; 1950-01-01 to current/open; source msha-controller-operator-history