# Relationship history for MSHA mine 1900290

Current hierarchy: **Thomas  Walsh → Boro Sand & Stone Corp → N Attleboro Plant**

- 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

- **operator_operates_mine:** Boro Sand & Stone Inc → N Attleboro Plant; 1950-01-01 to 1989-05-01; source msha-controller-operator-history
- **controller_controls_mine:** Joseph P  Rezza → N Attleboro Plant; 1950-01-01 to 1989-05-01; source msha-controller-operator-history
- **controller_controls_operator:** Joseph P  Rezza → Boro Sand & Stone Inc; 1950-01-01 to 1989-05-01; source msha-controller-operator-history
- **operator_operates_mine:** Boro Sand & Stone Corp → N Attleboro Plant; 1989-05-02 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Thomas  Walsh → N Attleboro Plant; 1989-05-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Thomas  Walsh → Boro Sand & Stone Corp; 1989-05-02 to current/open; source msha-controller-operator-history