# Relationship history for MSHA mine 4703582

Current hierarchy: **Blair E  Dillman → Prairie Sand & Gravel, Inc. → 2021 portable crusher**

- 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:** Blair E  Dillman → 2021 portable crusher; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Prairie Sand & Gravel, Inc. → 2021 portable crusher; 2010-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Blair E  Dillman → Prairie Sand & Gravel, Inc.; 2010-03-09 to current/open; source msha-controller-operator-history