# Relationship history for MSHA mine 0504151

Current hierarchy: **Weld County-Co → Weld County → PORTABLE SCREEN PLANT #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:** Weld County → PORTABLE SCREEN PLANT #2; 1986-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Weld County-Co → PORTABLE SCREEN PLANT #2; 1986-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Weld County-Co → Weld County; 1986-06-01 to current/open; source msha-controller-operator-history