# Relationship history for MSHA mine 0401957

Current hierarchy: **Hanson PLC → Southern Pacific Milling Company → Ventura River Pit & 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Southern Pacific Milling Company → Ventura River Pit & Mill; 1950-01-01 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_mine:** Koppers Company Inc → Ventura River Pit & Mill; 1950-01-01 to 1988-11-13; source msha-controller-operator-history
- **controller_controls_operator:** Koppers Company Inc → Southern Pacific Milling Company; 1950-01-01 to 1988-11-13; source msha-controller-operator-history
- **operator_operates_mine:** Southern Pacific Milling Company → Ventura River Pit & Mill; 1988-11-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hanson PLC → Ventura River Pit & Mill; 1988-11-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Hanson PLC → Southern Pacific Milling Company; 1988-11-14 to current/open; source msha-controller-operator-history