# Relationship history for MSHA mine 3800626

Current hierarchy: **Rio Tinto Group → Kennecott Ridgeway Mining Company → RIDGEWAY 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Ridgeway Mining Company → RIDGEWAY MINE; 1987-08-01 to 1989-06-29; source msha-controller-operator-history
- **controller_controls_mine:** British Petroleum Company PLC → RIDGEWAY MINE; 1987-08-01 to 1989-06-29; source msha-controller-operator-history
- **controller_controls_operator:** British Petroleum Company PLC → Ridgeway Mining Company; 1987-08-01 to 1989-06-29; source msha-controller-operator-history
- **operator_operates_mine:** Kennecott Ridgeway Mining Company → RIDGEWAY MINE; 1989-06-30 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Rio Tinto Group → RIDGEWAY MINE; 1989-06-30 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Rio Tinto Group → Kennecott Ridgeway Mining Company; 1989-06-30 to current/open; source msha-controller-operator-history