# Relationship history for MSHA mine 1511912

Current hierarchy: **Burchett Darvin & Wesley Blackburn → Cline Branch Coal Company Inc → No 3 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

- **controller_controls_mine:** Burchett Darvin & Wesley Blackburn → No 3 Mine; 1976-09-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Cline Branch Coal Company Inc → No 3 Mine; 1979-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Burchett Darvin & Wesley Blackburn → Cline Branch Coal Company Inc; 1979-05-01 to current/open; source msha-controller-operator-history