# Relationship history for MSHA mine 3002535

Current hierarchy: **Tracy  Saunders → W F Saunders & Sons Inc → Walburger 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:** Michael T  Saunders → Walburger Pit; 1950-01-01 to 2014-01-28; source msha-controller-operator-history
- **operator_operates_mine:** W F Saunders & Sons Inc → Walburger Pit; 1980-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael T  Saunders → W F Saunders & Sons Inc; 1980-07-01 to 2014-01-28; source msha-controller-operator-history
- **controller_controls_mine:** Tracy  Saunders → Walburger Pit; 2014-01-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tracy  Saunders → W F Saunders & Sons Inc; 2014-01-29 to current/open; source msha-controller-operator-history