# Relationship history for MSHA mine 2401961

Current hierarchy: **Pondera County-Mt → Pondera County → PORTABLE SCREEN PLANT**

- 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:** Pondera County → PORTABLE SCREEN PLANT; 1992-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Pondera County-Mt → PORTABLE SCREEN PLANT; 1992-04-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Pondera County-Mt → Pondera County; 1992-04-01 to current/open; source msha-controller-operator-history