# Relationship history for MSHA mine 4601832

Current hierarchy: **National Bulk Carriers → United Pocahontas Coal Company → No 17 Mine**

- 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:** United Pocahontas Coal Company → No 17 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** National Bulk Carriers → No 17 Mine; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** National Bulk Carriers → United Pocahontas Coal Company; 1950-01-01 to current/open; source msha-controller-operator-history