# Relationship history for MSHA mine 3607508

Current hierarchy: **Helfer Robert W & Ronald C Reefer → R & H Surface Mining → #1 Strip**

- 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:** R & H Surface Mining → #1 Strip; 1983-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Helfer Robert W & Ronald C Reefer → #1 Strip; 1983-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Helfer Robert W & Ronald C Reefer → R & H Surface Mining; 1983-10-01 to current/open; source msha-controller-operator-history