# Relationship history for MSHA mine 3500480

Current hierarchy: **Knife River Corporation → Knife River Corporation-Northwest → WILLAMETTE PORTABLE #4**

- 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:** Gary T  Baker → WILLAMETTE PORTABLE #4; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Dayton Sand & Gravel Company → WILLAMETTE PORTABLE #4; 1950-01-01 to 2003-11-30; source msha-controller-operator-history
- **controller_controls_mine:** Burch West Inc → WILLAMETTE PORTABLE #4; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Burch West Inc → Dayton Sand & Gravel Company; 1950-01-01 to 2003-11-30; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → WILLAMETTE PORTABLE #4; 1998-03-05 to 2023-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Baker Rock Resources West LLC → WILLAMETTE PORTABLE #4; 2003-12-01 to 2015-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Gary T  Baker → WILLAMETTE PORTABLE #4; 2003-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Gary T  Baker → Baker Rock Resources West LLC; 2003-12-01 to 2015-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Baker Rock Resources → WILLAMETTE PORTABLE #4; 2015-10-01 to 2022-01-19; source msha-controller-operator-history
- **controller_controls_operator:** Gary T  Baker → Baker Rock Resources; 2015-10-01 to 2022-01-19; source msha-controller-operator-history
- **operator_operates_mine:** Knife River Corporation-Northwest → WILLAMETTE PORTABLE #4; 2022-01-20 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Knife River Corporation-Northwest; 2022-01-20 to 2023-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Knife River Corporation → WILLAMETTE PORTABLE #4; 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