# Relationship history for MSHA mine 0100981

Current hierarchy: **Busby Grover → Grover Busby Coal Company → No 1 Pit 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:** Grover Busby Coal Company → No 1 Pit Mine; 1974-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Busby Grover → No 1 Pit Mine; 1974-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Busby Grover → Grover Busby Coal Company; 1974-12-01 to current/open; source msha-controller-operator-history