# Relationship history for MSHA mine 2100642

Current hierarchy: **Kohner Holding Company → Wabasha Sand  Gravel & Ready Mixed Company → 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

- **operator_operates_mine:** Wabasha Sand  Gravel & Ready Mixed Company → Wabasha Pit and Mill; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Steven  Kohner et al → Wabasha Pit and Mill; 1950-01-01 to 2023-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Steven  Kohner et al → Wabasha Sand  Gravel & Ready Mixed Company; 1950-01-01 to 2023-12-31; source msha-controller-operator-history
- **controller_controls_operator:** Robert S  Kohner et al → Wabasha Sand  Gravel & Ready Mixed Company; 1950-01-01 to 2023-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Kohner Holding Company → Wabasha Pit and Mill; 2024-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Kohner Holding Company → Wabasha Sand  Gravel & Ready Mixed Company; 2024-01-01 to current/open; source msha-controller-operator-history