# Relationship history for MSHA mine 4608321

Current hierarchy: **El Paso Energy Corp → Anr Coal-West Virginia Llc → Surface Mine #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:** El Paso Energy Corp → Surface Mine #21; 1992-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** El Paso Energy Corp → Surface Mine #21; 1993-05-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Greenbrier Coal Company → Surface Mine #21; 1993-07-01 to 1994-07-26; source msha-controller-operator-history
- **controller_controls_operator:** El Paso Energy Corp → Greenbrier Coal Company; 1993-07-01 to 1994-07-26; source msha-controller-operator-history
- **controller_controls_mine:** Gary Wayne  Johnson → Surface Mine #21; 1993-11-03 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Coal Rush Mining Inc → Surface Mine #21; 1994-07-27 to 1997-02-05; source msha-controller-operator-history
- **controller_controls_operator:** Gary Wayne  Johnson → Coal Rush Mining Inc; 1994-07-27 to 1997-02-05; source msha-controller-operator-history
- **operator_operates_mine:** Anr Coal-West Virginia Llc → Surface Mine #21; 1997-02-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** El Paso Energy Corp → Anr Coal-West Virginia Llc; 1997-02-06 to current/open; source msha-controller-operator-history