# Relationship history for MSHA mine 3400982

Current hierarchy: **King Douglas F → Urco Energy Inc → Kelley Coal 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Urco Energy Inc → Kelley Coal Strip; 1976-11-12 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** King Douglas F → Kelley Coal Strip; 1976-11-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** King Douglas F → Urco Energy Inc; 1976-11-12 to current/open; source msha-controller-operator-history