# Relationship history for MSHA mine 2101794

Current hierarchy: **Richard H  Johnson → Waseca Sand & Gravel Inc → Waseca Pit & 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:** Misgen'S Washed Sand & Gravel → Waseca Pit & Mill; 1950-01-01 to 1979-04-30; source msha-controller-operator-history
- **controller_controls_mine:** Michael  Misgen → Waseca Pit & Mill; 1950-01-01 to 1979-04-30; source msha-controller-operator-history
- **controller_controls_operator:** Michael  Misgen → Misgen'S Washed Sand & Gravel; 1950-01-01 to 1979-04-30; source msha-controller-operator-history
- **operator_operates_mine:** Waseca Sand & Gravel Inc → Waseca Pit & Mill; 1979-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Richard H  Johnson → Waseca Pit & Mill; 1979-05-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Richard H  Johnson → Waseca Sand & Gravel Inc; 1979-05-01 to current/open; source msha-controller-operator-history