# Relationship history for MSHA mine 1518085

Current hierarchy: **James River Coal Company → McCoy Elkhorn Coal Corp → Mine No 21**

- 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:** James River Coal Company → Mine No 21; 1988-09-28 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Zeigler Coal Holding Company → Mine No 21; 1997-03-01 to 1998-09-01; source msha-controller-operator-history
- **operator_operates_mine:** Matrix Coal Company → Mine No 21; 1998-08-01 to 1998-09-01; source msha-controller-operator-history
- **controller_controls_operator:** Zeigler Coal Holding Company → Matrix Coal Company; 1998-08-01 to 1998-09-01; source msha-controller-operator-history
- **operator_operates_mine:** Matrix Coal Company → Mine No 21; 1998-09-02 to 2000-01-02; source msha-controller-operator-history
- **controller_controls_mine:** Horizon Natural Resources Incorporated → Mine No 21; 1998-09-02 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Horizon Natural Resources Incorporated → Matrix Coal Company; 1998-09-02 to 2000-01-02; source msha-controller-operator-history
- **operator_operates_mine:** McCoy Elkhorn Coal Corp → Mine No 21; 2000-01-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** James River Coal Company → McCoy Elkhorn Coal Corp; 2000-01-03 to current/open; source msha-controller-operator-history