# Relationship history for MSHA mine 4500988

Current hierarchy: **Walt  Miles → Concrete Nor'West → Arlington 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Ross Sand & Gravel Company Inc → Arlington Pit; 1950-01-01 to 1983-04-07; source msha-controller-operator-history
- **controller_controls_mine:** Ross Sand & Gravel Company Inc → Arlington Pit; 1950-01-01 to 1983-04-07; source msha-controller-operator-history
- **controller_controls_operator:** Ross Sand & Gravel Company Inc → Ross Sand & Gravel Company Inc; 1950-01-01 to 1983-04-07; source msha-controller-operator-history
- **operator_operates_mine:** Concrete Nor'West → Arlington Pit; 1983-04-08 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Walt  Miles et al → Arlington Pit; 1983-04-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Walt  Miles et al → Concrete Nor'West; 1983-04-08 to current/open; source msha-controller-operator-history