# Relationship history for MSHA mine 5400050

Current hierarchy: **M C O Industries Inc → SAN LORENZO SAND & GRAVEL COMPANY → SAN LORENZO SAND & GRAVEL COMPANY**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Puerto Rico Concrete Products Inc → SAN LORENZO SAND & GRAVEL COMPANY; 1950-01-01 to 1983-01-11; source msha-controller-operator-history
- **controller_controls_mine:** Arturo  Pico Jr → SAN LORENZO SAND & GRAVEL COMPANY; 1950-01-01 to 1996-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Arturo  Pico Jr → Puerto Rico Concrete Products Inc; 1950-01-01 to 1983-01-11; source msha-controller-operator-history
- **operator_operates_mine:** SAN LORENZO SAND & GRAVEL COMPANY → SAN LORENZO SAND & GRAVEL COMPANY; 1983-01-12 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** M C O Industries Inc → SAN LORENZO SAND & GRAVEL COMPANY; 1983-01-12 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** M C O Industries Inc → SAN LORENZO SAND & GRAVEL COMPANY; 1983-01-12 to current/open; source msha-controller-operator-history