# Relationship history for MSHA mine 2102939

Current hierarchy: **MDU Resources Group Inc → Buffalo Bituminous Inc. → El Jay Cone**

- 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:** Buffalo Bituminous Inc → El Jay Cone; 1985-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Hicks Darrell E → El Jay Cone; 1985-05-01 to 2003-10-07; source msha-controller-operator-history
- **controller_controls_operator:** Hicks Darrell E → Buffalo Bituminous Inc; 1985-05-01 to 2003-10-07; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → El Jay Cone; 2003-10-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Buffalo Bituminous Inc; 2003-10-08 to current/open; source msha-controller-operator-history