# Relationship history for MSHA mine 1401526

Current hierarchy: **Mid America Materials Company → Hallett Materials → Portable #3-Sand/Wash 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:** Mid America Materials Company → Portable #3-Sand/Wash Plant; 1986-09-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Hallett Materials → Portable #3-Sand/Wash Plant; 1989-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mid America Materials Company → Hallett Materials; 1989-05-01 to current/open; source msha-controller-operator-history