# Relationship history for MSHA mine 3500536

Current hierarchy: **Nancy L Traverso → Parker Northwest Paving Company → RIVER ISLAND SAND & 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:** Parker Northwest Paving Company → RIVER ISLAND SAND & GRAVEL; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Parker-Northwest Inc → RIVER ISLAND SAND & GRAVEL; 1950-01-01 to 2015-12-22; source msha-controller-operator-history
- **controller_controls_operator:** Parker-Northwest Inc → Parker Northwest Paving Company; 1950-01-01 to 2015-12-22; source msha-controller-operator-history
- **controller_controls_mine:** Nancy L Traverso → RIVER ISLAND SAND & GRAVEL; 2015-12-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Nancy L Traverso → Parker Northwest Paving Company; 2015-12-23 to current/open; source msha-controller-operator-history