# Relationship history for MSHA mine 4404097

Current hierarchy: **Boyd Billy E → Billy B Coal Company → No 1 Mine**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** D & R Coal Company → No 1 Mine; 1975-01-01 to 1975-12-09; source msha-controller-operator-history
- **controller_controls_mine:** Church Dexter & Ron → No 1 Mine; 1975-01-01 to 1975-12-09; source msha-controller-operator-history
- **controller_controls_operator:** Church Dexter & Ron → D & R Coal Company; 1975-01-01 to 1975-12-09; source msha-controller-operator-history
- **operator_operates_mine:** Billy B Coal Company → No 1 Mine; 1975-12-10 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Boyd Billy E → No 1 Mine; 1975-12-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Boyd Billy E → Billy B Coal Company; 1975-12-10 to current/open; source msha-controller-operator-history