# Relationship history for MSHA mine 1510988

Current hierarchy: **Blackwell Ken → R & H 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:** R & H Coal Company → No 1 Mine; 1977-12-01 to 1979-04-08; source msha-controller-operator-history
- **controller_controls_mine:** Meade Herbert → No 1 Mine; 1977-12-01 to 1979-04-08; source msha-controller-operator-history
- **controller_controls_operator:** Meade Herbert → R & H Coal Company; 1977-12-01 to 1979-04-08; source msha-controller-operator-history
- **operator_operates_mine:** R & H Coal Company → No 1 Mine; 1979-04-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Blackwell Ken → No 1 Mine; 1979-04-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Blackwell Ken → R & H Coal Company; 1979-04-09 to current/open; source msha-controller-operator-history