# Relationship history for MSHA mine 3607734

Current hierarchy: **W Ruskin  Dressler → W Ruskin Dressler Coal → Nelson**

- 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:** W Ruskin Dressler Coal → Nelson; 1985-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** W Ruskin  Dressler → Nelson; 1985-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** W Ruskin  Dressler → W Ruskin Dressler Coal; 1985-09-01 to current/open; source msha-controller-operator-history