# Relationship history for MSHA mine 3002591

Current hierarchy: **Tracy M  Lawson → Lawson Sand & Gravel Inc → Lawson Sand & Gravel Incorporated**

- 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:** Lawson Sand & Gravel Inc → Lawson Sand & Gravel Incorporated; 1981-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Tracy M  Lawson → Lawson Sand & Gravel Incorporated; 1981-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tracy M  Lawson → Lawson Sand & Gravel Inc; 1981-06-01 to current/open; source msha-controller-operator-history