# Relationship history for MSHA mine 1500020

Current hierarchy: **David R  Harrod → Harrod Concrete & Stone Co Inc → Harrod Concrete & Stone Co Inc**

- 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:** Harrod Concrete & Stone Co Inc → Harrod Concrete & Stone Co Inc; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** David R  Harrod et al → Harrod Concrete & Stone Co Inc; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David R  Harrod et al → Harrod Concrete & Stone Co Inc; 1950-01-01 to current/open; source msha-controller-operator-history