# Relationship history for MSHA mine 2102586

Current hierarchy: **Paul  Duffek; Calvin  Krueger → Duffek Sand & Gravel Inc → Wabasha Pit And Mill**

- 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:** Paul  Duffek  et al → Wabasha Pit And Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Knapp Excavating → Wabasha Pit And Mill; 1950-01-01 to 1978-11-07; source msha-controller-operator-history
- **controller_controls_mine:** Knapp Howard L → Wabasha Pit And Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Knapp Howard L → Knapp Excavating; 1950-01-01 to 1978-11-07; source msha-controller-operator-history
- **operator_operates_mine:** Duffek Sand & Gravel Inc → Wabasha Pit And Mill; 1978-11-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Paul  Duffek  et al → Duffek Sand & Gravel Inc; 1978-11-08 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Calvin  Krueger  et al → Duffek Sand & Gravel Inc; 1978-11-08 to current/open; source msha-controller-operator-history