# Relationship history for MSHA mine 1900076

Current hierarchy: **S M Lorusso & Sons Inc → S M Lorusso & Sons Inc → West Roxbury Crushed 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** S M Lorusso & Sons Inc → West Roxbury Crushed Stone; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** West Roxbury Crushed Stone Company → West Roxbury Crushed Stone; 1950-01-01 to 1978-12-28; source msha-controller-operator-history
- **controller_controls_mine:** Browning-Ferris Industries Inc → West Roxbury Crushed Stone; 1950-01-01 to 1978-12-28; source msha-controller-operator-history
- **controller_controls_operator:** Browning-Ferris Industries Inc → West Roxbury Crushed Stone Company; 1950-01-01 to 1978-12-28; source msha-controller-operator-history
- **operator_operates_mine:** S M Lorusso & Sons Inc → West Roxbury Crushed Stone; 1978-12-29 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** S M Lorusso & Sons Inc → S M Lorusso & Sons Inc; 1978-12-29 to current/open; source msha-controller-operator-history