# Relationship history for MSHA mine 4604541

Current hierarchy: **West Ruby W → Crest Coal Company → No 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

- **controller_controls_mine:** Terry Coal Company → No 1 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Terry Coal Company → No 1 Mine; 1975-01-01 to 1975-12-11; source msha-controller-operator-history
- **controller_controls_operator:** Terry Coal Company → Terry Coal Company; 1975-01-01 to 1975-12-11; source msha-controller-operator-history
- **operator_operates_mine:** Crest Coal Company → No 1 Mine; 1975-12-12 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** West Ruby W → No 1 Mine; 1975-12-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** West Ruby W → Crest Coal Company; 1975-12-12 to current/open; source msha-controller-operator-history