# Relationship history for MSHA mine 3901471

Current hierarchy: **Richard C  Sweetman → Commerical Asphalt Div. of Spencer Quarries → Portable #1**

- 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:** Commerical Asphalt Div. of Spencer Quarries → Portable #1; 2002-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Richard C  Sweetman et al → Portable #1; 2002-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Richard C  Sweetman et al → Commerical Asphalt Div. of Spencer Quarries; 2002-04-01 to current/open; source msha-controller-operator-history