# Relationship history for MSHA mine 4602207

Current hierarchy: **Barnhill Robert E Sr → Energy Producers Inc → No 2 Surface**

- 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:** Key Mining Co → No 2 Surface; 1950-01-01 to 1975-03-14; source msha-controller-operator-history
- **controller_controls_mine:** Key Mining Co → No 2 Surface; 1950-01-01 to 1975-03-14; source msha-controller-operator-history
- **controller_controls_operator:** Key Mining Co → Key Mining Co; 1950-01-01 to 1975-03-14; source msha-controller-operator-history
- **controller_controls_mine:** Barnhill Robert E Sr → No 2 Surface; 1974-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Energy Producers Inc → No 2 Surface; 1975-03-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Barnhill Robert E Sr → Energy Producers Inc; 1975-03-15 to current/open; source msha-controller-operator-history