# Relationship history for MSHA mine 3200172

Current hierarchy: **Knife River Corporation → Strata Corporation → Portable #10**

- 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:** James R  Bradshaw et al → Portable #10; 1950-01-01 to 2026-03-22; source msha-controller-operator-history
- **operator_operates_mine:** Jamestown Sand & Gravel Inc → Portable #10; 1950-01-01 to 1989-06-20; source msha-controller-operator-history
- **controller_controls_mine:** Scrivens Charles → Portable #10; 1950-01-01 to 1989-06-20; source msha-controller-operator-history
- **controller_controls_operator:** Scrivens Charles → Jamestown Sand & Gravel Inc; 1950-01-01 to 1989-06-20; source msha-controller-operator-history
- **operator_operates_mine:** Lindberg Brothers Inc → Portable #10; 1989-06-21 to 2014-04-08; source msha-controller-operator-history
- **controller_controls_mine:** Jon Clifford  Lindberg → Portable #10; 1989-06-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Jon Clifford  Lindberg → Lindberg Brothers Inc; 1989-06-21 to 2014-04-08; source msha-controller-operator-history
- **operator_operates_mine:** Strata Corporation → Portable #10; 2014-04-09 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** James R  Bradshaw et al → Strata Corporation; 2014-04-09 to 2026-03-22; source msha-controller-operator-history
- **controller_controls_mine:** Knife River Corporation → Portable #10; 2026-03-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Knife River Corporation → Strata Corporation; 2026-03-23 to current/open; source msha-controller-operator-history