# Relationship history for MSHA mine 4201129

Current hierarchy: **Petro-Chem Inc → Westemco Inc → Westemco Mill**

- 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:** Western States Engineering & Milling Company → Westemco Mill; 1950-01-01 to 1980-01-14; source msha-controller-operator-history
- **controller_controls_mine:** Garrick Eldred M → Westemco Mill; 1950-01-01 to 1980-01-14; source msha-controller-operator-history
- **controller_controls_operator:** Garrick Eldred M → Western States Engineering & Milling Company; 1950-01-01 to 1980-01-14; source msha-controller-operator-history
- **operator_operates_mine:** Westemco Inc → Westemco Mill; 1980-01-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Petro-Chem Inc → Westemco Mill; 1980-01-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Petro-Chem Inc → Westemco Inc; 1980-01-15 to current/open; source msha-controller-operator-history