# Relationship history for MSHA mine 3606367

Current hierarchy: **Bigan M H → M H Bigan Coal Company → M H Bigan Strip Mine #2**

- 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

- **controller_controls_mine:** Bigan M H → M H Bigan Strip Mine #2; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** M H Bigan Coal Company → M H Bigan Strip Mine #2; 1977-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Bigan M H → M H Bigan Coal Company; 1977-04-01 to current/open; source msha-controller-operator-history