# Relationship history for MSHA mine 2901992

Current hierarchy: **U S Mineral Co Inc & Rayrock Yellowknife Resources → Western Ag-Minerals Company → Saunders Shafts**

- 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:** Pennzoil Company → Saunders Shafts; 1950-01-01 to 1985-11-14; source msha-controller-operator-history
- **operator_operates_mine:** Potash Producers Inc → Saunders Shafts; 1985-06-01 to 1985-11-14; source msha-controller-operator-history
- **controller_controls_operator:** Pennzoil Company → Potash Producers Inc; 1985-06-01 to 1985-11-14; source msha-controller-operator-history
- **operator_operates_mine:** Western Ag-Minerals Company → Saunders Shafts; 1985-11-15 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** U S Mineral Co Inc & Rayrock Yellowknife Resources → Saunders Shafts; 1985-11-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** U S Mineral Co Inc & Rayrock Yellowknife Resources → Western Ag-Minerals Company; 1985-11-15 to current/open; source msha-controller-operator-history