# Relationship history for MSHA mine 3603197

Current hierarchy: **Simon Larry T → Wempco → Lehigh Valley 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: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Lehigh Valley Sand & Gravel Company Inc → Lehigh Valley Sand & Gravel; 1950-01-01 to 1989-04-11; source msha-controller-operator-history
- **controller_controls_mine:** Tavianini Evo → Lehigh Valley Sand & Gravel; 1950-01-01 to 1989-04-11; source msha-controller-operator-history
- **controller_controls_operator:** Tavianini Evo → Lehigh Valley Sand & Gravel Company Inc; 1950-01-01 to 1989-04-11; source msha-controller-operator-history
- **operator_operates_mine:** Wempco → Lehigh Valley Sand & Gravel; 1989-04-12 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Simon Larry T → Lehigh Valley Sand & Gravel; 1989-04-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Simon Larry T → Wempco; 1989-04-12 to current/open; source msha-controller-operator-history