# Relationship history for MSHA mine 2402146

Current hierarchy: **Stevenson Robert → Northwest Excavating → NEW PORTABLE CRUSHER/SCREEN 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Northwest Excavating → NEW PORTABLE CRUSHER/SCREEN PIT; 1998-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Stevenson Robert → NEW PORTABLE CRUSHER/SCREEN PIT; 1998-07-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Stevenson Robert → Northwest Excavating; 1998-07-01 to current/open; source msha-controller-operator-history