# Relationship history for MSHA mine 1509789

Current hierarchy: **Whitt Phillip D → Whitmore Coal Inc → Prep Plant #1**

- 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:** Durr R C → Prep Plant #1; 1975-04-10 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** R C Durr Company Inc → Prep Plant #1; 1976-07-02 to 1978-07-31; source msha-controller-operator-history
- **controller_controls_operator:** Durr R C → R C Durr Company Inc; 1976-07-02 to 1978-07-31; source msha-controller-operator-history
- **operator_operates_mine:** Pilot Knob Processing Company Inc → Prep Plant #1; 1978-08-01 to 1979-09-11; source msha-controller-operator-history
- **controller_controls_mine:** Fred  Morgenstern et al → Prep Plant #1; 1978-08-01 to 1979-09-11; source msha-controller-operator-history
- **controller_controls_operator:** Fred  Morgenstern et al → Pilot Knob Processing Company Inc; 1978-08-01 to 1979-09-11; source msha-controller-operator-history
- **operator_operates_mine:** Whitmore Coal Inc → Prep Plant #1; 1979-09-12 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Whitt Phillip D → Prep Plant #1; 1979-09-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Whitt Phillip D → Whitmore Coal Inc; 1979-09-12 to current/open; source msha-controller-operator-history