# Relationship history for MSHA mine 4103507

Current hierarchy: **Chadwick-Williams → Southwest Road & Paving Company Inc → North Hills Screening 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Chadwick-Williams → North Hills Screening Plant; 1983-03-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Southwest Road & Paving Company Inc → North Hills Screening Plant; 1988-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Chadwick-Williams → Southwest Road & Paving Company Inc; 1988-02-01 to current/open; source msha-controller-operator-history