# Relationship history for MSHA mine 1901187

Current hierarchy: **Paul D  Nichols → NICHOLS SAND & GRAVEL → Pit 2**

- 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:** NICHOLS SAND & GRAVEL → Pit 2; 2009-04-20 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Paul D  Nichols → Pit 2; 2009-04-20 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Paul D  Nichols → NICHOLS SAND & GRAVEL; 2009-04-20 to current/open; source msha-controller-operator-history