# Relationship history for MSHA mine 3401640

Current hierarchy: **McCormick Inc → Northern Improvement Company → O'Hair Pit**

- 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:** McCormick Inc → O'Hair Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Northern Improvement Company → O'Hair Pit; 1988-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** McCormick Inc → Northern Improvement Company; 1988-03-01 to current/open; source msha-controller-operator-history