# Relationship history for MSHA mine 2101392

Current hierarchy: **MDU Resources Group Inc → Knife River Midwest LLC → Portable Rock Plant #2**

- 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

- **operator_operates_mine:** Knife River Midwest LLC → Portable Rock Plant #2; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Curtis G Roverud et al → Portable Rock Plant #2; 1950-01-01 to 2004-02-04; source msha-controller-operator-history
- **controller_controls_operator:** Curtis G Roverud et al → Knife River Midwest LLC; 1950-01-01 to 2004-02-04; source msha-controller-operator-history
- **controller_controls_operator:** Jeff C Roverud et al → Knife River Midwest LLC; 1950-01-01 to 2004-02-04; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → Portable Rock Plant #2; 2004-02-05 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Knife River Midwest LLC; 2004-02-05 to current/open; source msha-controller-operator-history