# Relationship history for MSHA mine 3503771

Current hierarchy: **Knife River Corporation → Knife River Corporation-Northwest → Ball Road Quarry**

- 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

- **controller_controls_mine:** Gary T  Baker → Ball Road Quarry; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → Ball Road Quarry; 1998-03-05 to 2023-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Baker Rock Resources → Ball Road Quarry; 2011-10-20 to 2022-01-17; source msha-controller-operator-history
- **controller_controls_operator:** Gary T  Baker → Baker Rock Resources; 2011-10-20 to 2022-01-17; source msha-controller-operator-history
- **operator_operates_mine:** Knife River Corporation-Northwest → Ball Road Quarry; 2022-01-18 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Knife River Corporation-Northwest; 2022-01-18 to 2023-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Knife River Corporation → Ball Road Quarry; 2023-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Knife River Corporation → Knife River Corporation-Northwest; 2023-06-01 to current/open; source msha-controller-operator-history