# Relationship history for MSHA mine 2500772

Current hierarchy: **Nebco Inc → Overland Sand & Gravel Company → Grigsby East Pit**

- 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:** Overland Sand & Gravel Company → Grigsby East Pit; 1950-01-01 to 2007-02-12; source msha-controller-operator-history
- **controller_controls_mine:** Vayden  Anderson et al → Grigsby East Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Vayden  Anderson et al → Overland Sand & Gravel Company; 1950-01-01 to 2007-02-12; source msha-controller-operator-history
- **operator_operates_mine:** Overland Sand & Gravel Company → Grigsby East Pit; 2007-02-13 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Nebco Inc → Grigsby East Pit; 2007-02-13 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Nebco Inc → Overland Sand & Gravel Company; 2007-02-13 to current/open; source msha-controller-operator-history