# Relationship history for MSHA mine 0402728

Current hierarchy: **Curtis  Hanford → Curtis Hanford Sand & Gravel → HANFORD**

- 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:** Preston Hanford Jr → HANFORD; 1950-01-01 to 1997-07-13; source msha-controller-operator-history
- **controller_controls_mine:** Hanford Preston → HANFORD; 1950-01-01 to 1997-07-13; source msha-controller-operator-history
- **controller_controls_operator:** Hanford Preston → Preston Hanford Jr; 1950-01-01 to 1997-07-13; source msha-controller-operator-history
- **operator_operates_mine:** Curtis Hanford Sand & Gravel → HANFORD; 1997-07-14 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Curtis  Hanford → HANFORD; 1997-07-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Curtis  Hanford → Curtis Hanford Sand & Gravel; 1997-07-14 to current/open; source msha-controller-operator-history