# Relationship history for MSHA mine 0203487

Current hierarchy: **Navajo Nation → Navajo Engineering and Construction Authority → Teec Nos Pos Gravel Pit**

- 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 Engineering and Construction Authority → Teec Nos Pos Gravel Pit; 2023-11-21 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Navajo Nation → Teec Nos Pos Gravel Pit; 2023-11-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Navajo Nation → Navajo Engineering and Construction Authority; 2023-11-21 to current/open; source msha-controller-operator-history