# Relationship history for MSHA mine 0504511

Current hierarchy: **Tusco Inc → Calco Inc → Box Canyon #1**

- 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

- **controller_controls_mine:** Tusco Inc → Box Canyon #1; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Calco Inc → Box Canyon #1; 1992-10-01 to 1994-04-30; source msha-controller-operator-history
- **controller_controls_operator:** Tusco Inc → Calco Inc; 1992-10-01 to 1994-04-30; source msha-controller-operator-history
- **operator_operates_mine:** Contract Blasting Services → Box Canyon #1; 1994-05-01 to 1995-03-27; source msha-controller-operator-history
- **controller_controls_mine:** Engwis Jan-Martin Yenter Et Al → Box Canyon #1; 1994-05-01 to 1995-03-27; source msha-controller-operator-history
- **controller_controls_operator:** Engwis Jan-Martin Yenter Et Al → Contract Blasting Services; 1994-05-01 to 1995-03-27; source msha-controller-operator-history
- **operator_operates_mine:** Calco Inc → Box Canyon #1; 1995-03-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Tusco Inc → Calco Inc; 1995-03-28 to current/open; source msha-controller-operator-history