# Relationship history for MSHA mine 4200879

Current hierarchy: **Grand Oil & Transport Company → Grand Oil & Transport Company → Dunn Sand And Gravel Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-18T09:31:49.615908+00:00

## Valid-time edges

- **operator_operates_mine:** Grand Oil & Transport Company → Dunn Sand And Gravel Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Grand Oil & Transport Company → Dunn Sand And Gravel Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Grand Oil & Transport Company → Grand Oil & Transport Company; 1950-01-01 to current/open; source msha-controller-operator-history