# Relationship history for MSHA mine 4500638

Current hierarchy: **Stephen  Nielsen → Holroyd Company Inc → Meadow Park Pit Or Meadow Park Pit & Mil**

- 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:** Holroyd Company Inc → Meadow Park Pit Or Meadow Park Pit & Mil; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Stephen  Nielsen  et al → Meadow Park Pit Or Meadow Park Pit & Mil; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Stephen  Nielsen  et al → Holroyd Company Inc; 1950-01-01 to current/open; source msha-controller-operator-history