# Relationship history for MSHA mine 0201449

Current hierarchy: **Salcido Johnny F → Douglas Ready Mix → Douglas Ready Mix**

- 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:** Salcido Sand & Gravel Inc → Douglas Ready Mix; 1950-01-01 to 1983-08-22; source msha-controller-operator-history
- **controller_controls_mine:** Salcido Juan → Douglas Ready Mix; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Salcido Juan → Salcido Sand & Gravel Inc; 1950-01-01 to 1983-08-22; source msha-controller-operator-history
- **operator_operates_mine:** Douglas Ready Mix → Douglas Ready Mix; 1983-08-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Salcido Johnny F → Douglas Ready Mix; 1983-08-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Salcido Johnny F → Douglas Ready Mix; 1983-08-23 to current/open; source msha-controller-operator-history