# Relationship history for MSHA mine 4201522

Current hierarchy: **Harper Investments Inc → Harper Sand & Gravel Inc → Harper Sand & Gravel Pit #4**

- 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

- **operator_operates_mine:** Harper Sand & Gravel Inc → Harper Sand & Gravel Pit #4; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Harper Investments Inc → Harper Sand & Gravel Pit #4; 1978-03-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Harper Investments Inc → Harper Sand & Gravel Inc; 1978-03-09 to current/open; source msha-controller-operator-history