# Relationship history for MSHA mine 4406420

Current hierarchy: **William N Johnston; Clara May Coffey → Shenandoah Stone → Shenandoah Asphalt, Inc t/a Shenandoah Stone**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Shenandoah Stone → Shenandoah Asphalt, Inc t/a Shenandoah S; 1987-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Abner N  Johnson IV → Shenandoah Asphalt, Inc t/a Shenandoah S; 1987-09-01 to 2025-12-14; source msha-controller-operator-history
- **controller_controls_operator:** Abner N  Johnson IV → Shenandoah Stone; 1987-09-01 to 2025-12-14; source msha-controller-operator-history
- **controller_controls_mine:** William N Johnston et al → Shenandoah Asphalt, Inc t/a Shenandoah S; 2025-12-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** William N Johnston et al → Shenandoah Stone; 2025-12-15 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Clara May Coffey et al → Shenandoah Stone; 2025-12-15 to current/open; source msha-controller-operator-history