# Relationship history for MSHA mine 4703644

Current hierarchy: **USS Holdings Inc → U.S.Silica Energy Company → Sparta, WI 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** USS Holdings Inc → Sparta, WI Plant; 1996-03-09 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** U S Silica Company → Sparta, WI Plant; 2012-04-10 to 2025-03-27; source msha-controller-operator-history
- **controller_controls_operator:** USS Holdings Inc → U S Silica Company; 2012-04-10 to 2025-03-27; source msha-controller-operator-history
- **operator_operates_mine:** U.S.Silica Energy Company → Sparta, WI Plant; 2025-03-28 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** USS Holdings Inc → Sparta, WI Plant; 2025-03-28 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** USS Holdings Inc → U.S.Silica Energy Company; 2025-03-28 to current/open; source msha-controller-operator-history