# Relationship history for MSHA mine 4605156

Current hierarchy: **Bortz George H Iii → Bortz Coal Company → Stewartstown 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

- **operator_operates_mine:** Bortz Coal Company → Stewartstown Strip; 1976-04-20 to 1977-12-05; source msha-controller-operator-history
- **controller_controls_mine:** Bortz George H Iii → Stewartstown Strip; 1976-04-20 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bortz George H Iii → Bortz Coal Company; 1976-04-20 to 1977-12-05; source msha-controller-operator-history
- **operator_operates_mine:** West Run Enterprises Inc → Stewartstown Strip; 1977-12-06 to 1979-02-27; source msha-controller-operator-history
- **controller_controls_mine:** Stiles F W → Stewartstown Strip; 1977-12-06 to 1979-02-27; source msha-controller-operator-history
- **controller_controls_operator:** Stiles F W → West Run Enterprises Inc; 1977-12-06 to 1979-02-27; source msha-controller-operator-history
- **operator_operates_mine:** Bortz Coal Company → Stewartstown Strip; 1979-02-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bortz George H Iii → Bortz Coal Company; 1979-02-28 to current/open; source msha-controller-operator-history