# Relationship history for MSHA mine 0201893

Current hierarchy: **Navajo County-AZ → Navajo County → Martison 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

- **operator_operates_mine:** Navajo County → Martison Wash Plant; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Navajo County-AZ → Martison Wash Plant; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Navajo County-AZ → Navajo County; 1978-03-09 to current/open; source msha-controller-operator-history