# Relationship history for MSHA mine 3605507

Current hierarchy: **Corgan William H → Northeast Energy Company → Corgan Precleaning Plant**

- 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

- **controller_controls_mine:** Corgan William H → Corgan Precleaning Plant; 1970-02-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Northeast Energy Company → Corgan Precleaning Plant; 1975-03-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Corgan William H → Northeast Energy Company; 1975-03-06 to current/open; source msha-controller-operator-history