# Relationship history for MSHA mine 4300436

Current hierarchy: **Charles  Bickford → Bickford's Quarry LLC → BICKFORD'S QUARRY**

- 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

- **operator_operates_mine:** Bickford's Quarry LLC → BICKFORD'S QUARRY; 1989-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Charles  Bickford → BICKFORD'S QUARRY; 1989-08-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Charles  Bickford → Bickford's Quarry LLC; 1989-08-01 to current/open; source msha-controller-operator-history