# Relationship history for MSHA mine 4607964

Current hierarchy: **Zeigler Coal Holding Company → Western Mingo Coal 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Shell Oil Company → No 1 Surface Mine; 1987-09-12 to 1992-11-23; source msha-controller-operator-history
- **operator_operates_mine:** Western Mingo Coal Company → No 1 Surface Mine; 1990-10-01 to 1992-11-23; source msha-controller-operator-history
- **controller_controls_operator:** Shell Oil Company → Western Mingo Coal Company; 1990-10-01 to 1992-11-23; source msha-controller-operator-history
- **operator_operates_mine:** Western Mingo Coal Company → No 1 Surface Mine; 1992-11-24 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Zeigler Coal Holding Company → No 1 Surface Mine; 1992-11-24 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Zeigler Coal Holding Company → Western Mingo Coal Company; 1992-11-24 to current/open; source msha-controller-operator-history