# Relationship history for MSHA mine 0503839

Current hierarchy: **Don  Kehn → Don Kehn Construction Inc → Wyoming Hereford Ranch 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Don  Kehn → Wyoming Hereford Ranch Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Don Kehn Construction Inc → Wyoming Hereford Ranch Pit; 1983-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Don  Kehn → Don Kehn Construction Inc; 1983-03-01 to current/open; source msha-controller-operator-history