# Relationship history for MSHA mine 2301620

Current hierarchy: **Cobb Ronnie → Cobb'S Backhoe Service → Cobb Sand & Gravel**

- 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

- **operator_operates_mine:** Luther Cobb Gravel Company → Cobb Sand & Gravel; 1950-01-01 to 1983-03-22; source msha-controller-operator-history
- **controller_controls_mine:** Cobb Luther → Cobb Sand & Gravel; 1950-01-01 to 1983-03-22; source msha-controller-operator-history
- **controller_controls_operator:** Cobb Luther → Luther Cobb Gravel Company; 1950-01-01 to 1983-03-22; source msha-controller-operator-history
- **operator_operates_mine:** Cobb'S Backhoe Service → Cobb Sand & Gravel; 1983-03-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Cobb Ronnie → Cobb Sand & Gravel; 1983-03-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Cobb Ronnie → Cobb'S Backhoe Service; 1983-03-23 to current/open; source msha-controller-operator-history