# Relationship history for MSHA mine 2002670

Current hierarchy: **Leon E  Schworm → Schworm Inc → Mason County Pit**

- 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:** Leon E  Schworm → Mason County Pit; 1979-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Schworm Inc → Mason County Pit; 1981-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Leon E  Schworm → Schworm Inc; 1981-08-01 to current/open; source msha-controller-operator-history