# Relationship history for MSHA mine 1900992

Current hierarchy: **Dauphinais Albert A → North Wilbraham Sand & Gravel & Concrete Co Inc → Rondeau Pit And Mill**

- 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:** North Wilbraham Sand & Gravel & Concrete Co Inc → Rondeau Pit And Mill; 1981-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Dauphinais Albert A Et Al → Rondeau Pit And Mill; 1981-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Dauphinais Albert A Et Al → North Wilbraham Sand & Gravel & Concrete Co Inc; 1981-10-01 to current/open; source msha-controller-operator-history