# Relationship history for MSHA mine 3600929

Current hierarchy: **Mon Valley Steel Company Inc → Tunnelton Mining Company → Marion 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:** Tunnelton Mining Company → Marion Mine; 1950-01-01 to 1992-09-25; source msha-controller-operator-history
- **controller_controls_mine:** Pennsylvania Power & Light Company → Marion Mine; 1950-01-01 to 1992-09-25; source msha-controller-operator-history
- **controller_controls_operator:** Pennsylvania Power & Light Company → Tunnelton Mining Company; 1950-01-01 to 1992-09-25; source msha-controller-operator-history
- **operator_operates_mine:** Tunnelton Mining Company → Marion Mine; 1992-09-26 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mon Valley Steel Company Inc → Marion Mine; 1992-09-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mon Valley Steel Company Inc → Tunnelton Mining Company; 1992-09-26 to current/open; source msha-controller-operator-history