# Relationship history for MSHA mine 3002820

Current hierarchy: **Schmidz J → Tri-County Crushed Stone Inc → Tri-County Crushed 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:** Tri-County Crushed Stone Inc → Tri-County Crushed Stone; 1987-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Schmidz J → Tri-County Crushed Stone; 1987-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Schmidz J → Tri-County Crushed Stone Inc; 1987-10-01 to current/open; source msha-controller-operator-history