# Relationship history for MSHA mine 3607233

Current hierarchy: **Bortz George H Iii → Falco Coal Company Inc → Walter'S 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Bortz George H Iii → Walter'S No 1 Strip; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Falco Coal Company Inc → Walter'S No 1 Strip; 1981-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bortz George H Iii → Falco Coal Company Inc; 1981-11-01 to current/open; source msha-controller-operator-history