# Relationship history for MSHA mine 2301977

Current hierarchy: **Marion County-MO → Marion County Highway Department → Marion County Sand & Gravel**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Marion County Highway Department → Marion County Sand & Gravel; 1987-12-01 to 1988-01-01; source msha-controller-operator-history
- **controller_controls_mine:** Marion County-MO → Marion County Sand & Gravel; 1987-12-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Marion County-MO → Marion County Highway Department; 1987-12-01 to 1988-01-01; source msha-controller-operator-history
- **operator_operates_mine:** Dam Red-E-Mix Inc → Marion County Sand & Gravel; 1988-01-02 to 1989-06-13; source msha-controller-operator-history
- **controller_controls_mine:** Clarkson Construction Co et al → Marion County Sand & Gravel; 1988-01-02 to 1989-06-13; source msha-controller-operator-history
- **controller_controls_operator:** Clarkson Construction Co et al → Dam Red-E-Mix Inc; 1988-01-02 to 1989-06-13; source msha-controller-operator-history
- **operator_operates_mine:** Marion County Highway Department → Marion County Sand & Gravel; 1989-06-14 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Marion County-MO → Marion County Highway Department; 1989-06-14 to current/open; source msha-controller-operator-history