# Relationship history for MSHA mine 2400487

Current hierarchy: **Knife River Corporation → Knife River Missoula → Polson Wash 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Ready Mix Concrete Company → Polson Wash Plant; 1950-01-01 to 1984-05-02; source msha-controller-operator-history
- **controller_controls_mine:** Carl A  Seifert → Polson Wash Plant; 1950-01-01 to 1984-05-02; source msha-controller-operator-history
- **controller_controls_operator:** Carl A  Seifert → Ready Mix Concrete Company; 1950-01-01 to 1984-05-02; source msha-controller-operator-history
- **operator_operates_mine:** Polson Ready Mix Concrete Inc → Polson Wash Plant; 1984-05-03 to 2000-09-30; source msha-controller-operator-history
- **controller_controls_mine:** Frank A  Thomas  et al → Polson Wash Plant; 1984-05-03 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Frank A  Thomas  et al → Polson Ready Mix Concrete Inc; 1984-05-03 to 2000-09-30; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → Polson Wash Plant; 1999-09-01 to 2023-05-31; source msha-controller-operator-history
- **operator_operates_mine:** Polson Ready Mix → Polson Wash Plant; 2000-10-01 to 2002-06-23; source msha-controller-operator-history
- **controller_controls_mine:** MDU Resources Group Inc → Polson Wash Plant; 2000-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Polson Ready Mix; 2000-10-01 to 2002-06-23; source msha-controller-operator-history
- **operator_operates_mine:** JTL Group → Polson Wash Plant; 2002-06-24 to 2005-03-31; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → JTL Group; 2002-06-24 to 2005-03-31; source msha-controller-operator-history
- **operator_operates_mine:** Polson Ready Mix → Polson Wash Plant; 2005-04-01 to 2008-02-10; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Polson Ready Mix; 2005-04-01 to 2008-02-10; source msha-controller-operator-history
- **operator_operates_mine:** Knife River Missoula → Polson Wash Plant; 2008-02-11 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** MDU Resources Group Inc → Knife River Missoula; 2008-02-11 to 2023-05-31; source msha-controller-operator-history
- **controller_controls_mine:** Knife River Corporation → Polson Wash Plant; 2023-06-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Knife River Corporation → JTL Group; 2023-06-01 to 2005-03-31; source msha-controller-operator-history
- **controller_controls_operator:** Knife River Corporation → Knife River Missoula; 2023-06-01 to current/open; source msha-controller-operator-history