# Relationship history for MSHA mine 2700359

Current hierarchy: **Boston Sand & Gravel Company → Manchester Sand, Gravel & Cement Co. Inc. → Manchester Sand & Gravel Bow Pit**

- 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

- **controller_controls_mine:** Boston Sand & Gravel Company → Manchester Sand & Gravel Bow Pit; 1979-07-10 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Manchester Sand, Gravel & Cement Co. Inc. → Manchester Sand & Gravel Bow Pit; 2001-02-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Boston Sand & Gravel Company → Manchester Sand, Gravel & Cement Co. Inc.; 2001-02-14 to current/open; source msha-controller-operator-history