# Relationship history for MSHA mine 4604521

Current hierarchy: **Mc Kenzie Eugene A → Mc Kenzie Specialty Company → No 1 Surface Mine**

- 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:** Mc Kenzie Specialty Company → No 1 Surface Mine; 1975-02-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mc Kenzie Eugene A → No 1 Surface Mine; 1975-02-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mc Kenzie Eugene A → Mc Kenzie Specialty Company; 1975-02-14 to current/open; source msha-controller-operator-history