# Relationship history for MSHA mine 1800682

Current hierarchy: **Duckworth John & Richard → J & R Coal Company → Richard Duckworth No 1 Strip**

- 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:** J & R Coal Company → Richard Duckworth No 1 Strip; 1981-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Duckworth John & Richard → Richard Duckworth No 1 Strip; 1981-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Duckworth John & Richard → J & R Coal Company; 1981-03-01 to current/open; source msha-controller-operator-history