# Relationship history for MSHA mine 1508430

Current hierarchy: **Cox William A → Grassy Fork Coal Company → No 2 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:** Cox William A → No 2 Mine; 1974-10-22 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Grassy Fork Coal Company → No 2 Mine; 1975-06-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Cox William A → Grassy Fork Coal Company; 1975-06-10 to current/open; source msha-controller-operator-history