# Relationship history for MSHA mine 3900225

Current hierarchy: **Knife River Corporation → Concrete Materials-Div/Sweetman Construction Co → Rice Street Sandplant**

- 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

- **operator_operates_mine:** Concrete Materials-Div/Sweetman Construction Co → Rice Street Sandplant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Gerald P  Sweetman → Rice Street Sandplant; 1950-01-01 to 2018-10-03; source msha-controller-operator-history
- **controller_controls_operator:** Gerald P  Sweetman → Concrete Materials-Div/Sweetman Construction Co; 1950-01-01 to 2018-10-03; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → Rice Street Sandplant; 2018-10-04 to 2023-05-31; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Concrete Materials-Div/Sweetman Construction Co; 2018-10-04 to 2023-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Knife River Corporation → Rice Street Sandplant; 2023-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Knife River Corporation → Concrete Materials-Div/Sweetman Construction Co; 2023-06-01 to current/open; source msha-controller-operator-history