# Relationship history for MSHA mine 4201822

Current hierarchy: **Murphy Nicholas L Jr → Murphy Mining Company → Snow Drift**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Murphy Nicholas L Jr → Snow Drift; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Murphy Mining Company → Snow Drift; 1983-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Murphy Nicholas L Jr → Murphy Mining Company; 1983-06-01 to current/open; source msha-controller-operator-history