# Relationship history for MSHA mine 0900876

Current hierarchy: **Blankenship Milton & Pope Welch → Snapping Shoals Sand & Gravel Company → Snapping Shoals Sand And Gravel Company**

- 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:** Snapping Shoals Sand Company → Snapping Shoals Sand And Gravel Company; 1950-01-01 to 1986-08-25; source msha-controller-operator-history
- **controller_controls_mine:** Davidson E C → Snapping Shoals Sand And Gravel Company; 1950-01-01 to 1986-08-25; source msha-controller-operator-history
- **controller_controls_operator:** Davidson E C → Snapping Shoals Sand Company; 1950-01-01 to 1986-08-25; source msha-controller-operator-history
- **operator_operates_mine:** Snapping Shoals Sand & Gravel Company → Snapping Shoals Sand And Gravel Company; 1986-08-26 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Blankenship Milton & Pope Welch → Snapping Shoals Sand And Gravel Company; 1986-08-26 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Blankenship Milton & Pope Welch → Snapping Shoals Sand & Gravel Company; 1986-08-26 to current/open; source msha-controller-operator-history