# Relationship history for MSHA mine 3303343

Current hierarchy: **Kenmore Construction Company Inc → American Sand & Gravel → Suffield 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** American Sand & Gravel → Suffield Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Kenmore Construction Company Inc → Suffield Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kenmore Construction Company Inc → American Sand & Gravel; 1950-01-01 to current/open; source msha-controller-operator-history