# Relationship history for MSHA mine 3609920

Current hierarchy: **US Anthracite Corp → Ridge Coal Co. → Ridge Coal Breaker**

- 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:** Ridge Coal Co. → Ridge Coal Breaker; 2011-03-16 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** US Anthracite Corp → Ridge Coal Breaker; 2011-03-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** US Anthracite Corp → Ridge Coal Co.; 2011-03-16 to current/open; source msha-controller-operator-history