# Relationship history for MSHA mine 2003018

Current hierarchy: **Henry M  Mason III → Mason Sand & Gravel Incorporated → Wash Plant**

- 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

- **controller_controls_mine:** Henry M  Mason III → Wash Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Mason Sand & Gravel Incorporated → Wash Plant; 1997-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Henry M  Mason III → Mason Sand & Gravel Incorporated; 1997-06-01 to current/open; source msha-controller-operator-history