# Relationship history for MSHA mine 2501156

Current hierarchy: **Robb Ted → Tri City Sand & Gravel → Tri City 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Tri City Sand & Gravel → Tri City Sand & Gravel; 1994-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Robb Ted → Tri City Sand & Gravel; 1994-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Robb Ted → Tri City Sand & Gravel; 1994-03-01 to current/open; source msha-controller-operator-history