# Relationship history for MSHA mine 3901178

Current hierarchy: **Brewster Douglas → Sisseton Ready Mix → Sisseton Ready Mix And 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: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Sisseton Ready Mix → Sisseton Ready Mix And Plant; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Brewster Douglas → Sisseton Ready Mix And Plant; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Brewster Douglas → Sisseton Ready Mix; 1979-01-01 to current/open; source msha-controller-operator-history