# Relationship history for MSHA mine 4703292

Current hierarchy: **Polk County - WI → Polk County Highway Dept. → Screening 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **controller_controls_mine:** Polk County - WI → Screening Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Polk County Highway Dept. → Screening Plant; 2001-11-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Polk County - WI → Polk County Highway Dept.; 2001-11-06 to current/open; source msha-controller-operator-history