# Relationship history for MSHA mine 2500944

Current hierarchy: **Vrbas Gaylord → Vrbas Sand & Gravel → VRBAS SAND AND GRAVEL**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Vrbas Sand & Gravel → VRBAS SAND AND GRAVEL; 1979-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Vrbas Gaylord → VRBAS SAND AND GRAVEL; 1979-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vrbas Gaylord → Vrbas Sand & Gravel; 1979-07-01 to current/open; source msha-controller-operator-history