# Relationship history for MSHA mine 2501057

Current hierarchy: **Nebco Inc → Overland Sand & Gravel Company → Blue Chip 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Vayden  Anderson et al → Blue Chip Pit; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Zieg Sand & Gravel → Blue Chip Pit; 1986-04-01 to 1988-08-01; source msha-controller-operator-history
- **controller_controls_mine:** Zieg Tim → Blue Chip Pit; 1986-04-01 to 1988-08-01; source msha-controller-operator-history
- **controller_controls_operator:** Zieg Tim → Zieg Sand & Gravel; 1986-04-01 to 1988-08-01; source msha-controller-operator-history
- **operator_operates_mine:** Overland Sand & Gravel Company → Blue Chip Pit; 1988-08-02 to 2007-02-12; source msha-controller-operator-history
- **controller_controls_operator:** Vayden  Anderson et al → Overland Sand & Gravel Company; 1988-08-02 to 2007-02-12; source msha-controller-operator-history
- **operator_operates_mine:** Overland Sand & Gravel Company → Blue Chip Pit; 2007-02-13 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Nebco Inc → Blue Chip 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