# Relationship history for MSHA mine 3607597

Current hierarchy: **Berzonsky M E → M E Berzonsky Coal Company → B & B #1 Mine**

- 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:** M E Berzonsky Coal Company → B & B #1 Mine; 1984-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Berzonsky M E → B & B #1 Mine; 1984-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Berzonsky M E → M E Berzonsky Coal Company; 1984-07-01 to current/open; source msha-controller-operator-history