# Relationship history for MSHA mine 4606001

Current hierarchy: **Burge Billy E → Milford Mining Company Inc → 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:** Milford Mining Company Inc → No 1 Strip; 1979-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Burge Billy E → No 1 Strip; 1979-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Burge Billy E → Milford Mining Company Inc; 1979-05-01 to current/open; source msha-controller-operator-history