# Relationship history for MSHA mine 2501036

Current hierarchy: **Alice Jean  Backhaus → Backus Sand & Gravel → BACKHAUS 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

- **controller_controls_mine:** Alice Jean  Backhaus → BACKHAUS SAND & GRAVEL; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Northeast Sand & Gravel Inc → BACKHAUS SAND & GRAVEL; 1985-06-01 to 1991-09-15; source msha-controller-operator-history
- **controller_controls_mine:** James H Jansen → BACKHAUS SAND & GRAVEL; 1985-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** James H Jansen → Northeast Sand & Gravel Inc; 1985-06-01 to 1991-09-15; source msha-controller-operator-history
- **operator_operates_mine:** Backus Sand & Gravel → BACKHAUS SAND & GRAVEL; 1991-09-16 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Alice Jean  Backhaus → Backus Sand & Gravel; 1991-09-16 to current/open; source msha-controller-operator-history