# Relationship history for MSHA mine 4000018

Current hierarchy: **Cocke County-TN → Cocke County Highway Dept → Smith Quarry**

- 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:** Cocke County Highway Dept → Smith Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Cocke County-TN → Smith Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Cocke County-TN → Cocke County Highway Dept; 1950-01-01 to current/open; source msha-controller-operator-history