# Relationship history for MSHA mine 4001681

Current hierarchy: **Powers Delmar → Powers Brothers 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Powers Brothers Coal Company → No 1 Mine; 1974-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Powers Delmar → No 1 Mine; 1974-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Powers Delmar → Powers Brothers Coal Company; 1974-12-01 to current/open; source msha-controller-operator-history