# Relationship history for MSHA mine 4406678

Current hierarchy: **Lewis C  Walker → Walker Sand & Stone → WALKER SAND & STONE**

- 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

- **operator_operates_mine:** Walker Sand & Stone → WALKER SAND & STONE; 1991-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Lewis C  Walker → WALKER SAND & STONE; 1991-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Lewis C  Walker → Walker Sand & Stone; 1991-11-01 to current/open; source msha-controller-operator-history