# Relationship history for MSHA mine 3400929

Current hierarchy: **Roger E  Dahlgren → Dahlgren Contracting Inc → George 1 Strip**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Roger E  Dahlgren → George 1 Strip; 1975-09-25 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Richardson Construction Company → George 1 Strip; 1975-10-24 to 1976-08-18; source msha-controller-operator-history
- **controller_controls_mine:** Kenneth  Richardson et al → George 1 Strip; 1975-10-24 to 1976-08-18; source msha-controller-operator-history
- **controller_controls_operator:** Kenneth  Richardson et al → Richardson Construction Company; 1975-10-24 to 1976-08-18; source msha-controller-operator-history
- **operator_operates_mine:** Dahlgren Contracting Inc → George 1 Strip; 1976-08-19 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Roger E  Dahlgren → Dahlgren Contracting Inc; 1976-08-19 to current/open; source msha-controller-operator-history