# Relationship history for MSHA mine 3901405

Current hierarchy: **Yankton County-S D → Yankton County Highway Department → 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Yankton County Highway Department → Portable Crusher; 1994-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Yankton County-S D → Portable Crusher; 1994-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Yankton County-S D → Yankton County Highway Department; 1994-10-01 to current/open; source msha-controller-operator-history