# Relationship history for MSHA mine 1506909

Current hierarchy: **Harris Sterl E → Harris Coal Co → 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:** River Valley Coal Company Inc → No 1 Mine; 1950-01-01 to 1974-01-07; source msha-controller-operator-history
- **controller_controls_mine:** River Valley Coal Company Inc → No 1 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** River Valley Coal Company Inc → River Valley Coal Company Inc; 1950-01-01 to 1974-01-07; source msha-controller-operator-history
- **operator_operates_mine:** Harris Coal Co → No 1 Mine; 1974-01-08 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Harris Sterl E → No 1 Mine; 1974-01-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harris Sterl E → Harris Coal Co; 1974-01-08 to current/open; source msha-controller-operator-history