# Relationship history for MSHA mine 1506705

Current hierarchy: **Howell Junior → Big Springs Coal Company Inc → 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:** King Coal Company Inc → No 1 Mine; 1973-06-08 to 1974-04-17; source msha-controller-operator-history
- **controller_controls_mine:** King Everage → No 1 Mine; 1973-06-08 to 1974-04-17; source msha-controller-operator-history
- **controller_controls_operator:** King Everage → King Coal Company Inc; 1973-06-08 to 1974-04-17; source msha-controller-operator-history
- **operator_operates_mine:** Big Springs Coal Company Inc → No 1 Mine; 1974-04-18 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Howell Junior → No 1 Mine; 1974-04-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Howell Junior → Big Springs Coal Company Inc; 1974-04-18 to current/open; source msha-controller-operator-history