# Relationship history for MSHA mine 3301467

Current hierarchy: **Ernst Aggregates Inc → Ernst Gravel Company → Ernst Gravel Company Plant No 2**

- 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

- **operator_operates_mine:** Ernst Gravel Company → Ernst Gravel Company Plant No 2; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Ernst Aggregates Inc → Ernst Gravel Company Plant No 2; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Ernst Aggregates Inc → Ernst Gravel Company; 1950-01-01 to current/open; source msha-controller-operator-history