# Relationship history for MSHA mine 3606173

Current hierarchy: **Smith James A & Ruth R → A A Smith Coal Company → Hilbert Tract**

- 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:** A A Smith Coal Company → Hilbert Tract; 1976-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Smith James A & Ruth R → Hilbert Tract; 1976-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Smith James A & Ruth R → A A Smith Coal Company; 1976-07-01 to current/open; source msha-controller-operator-history