# Relationship history for MSHA mine 3301486

Current hierarchy: **Schweitzer Roy B → Rack Sand Inc → RACK SAND, INC.**

- 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:** George L Rack Inc → RACK SAND, INC.; 1950-01-01 to 1985-02-19; source msha-controller-operator-history
- **controller_controls_mine:** Rack George B → RACK SAND, INC.; 1950-01-01 to 1985-02-19; source msha-controller-operator-history
- **controller_controls_operator:** Rack George B → George L Rack Inc; 1950-01-01 to 1985-02-19; source msha-controller-operator-history
- **operator_operates_mine:** Rack Sand Inc → RACK SAND, INC.; 1985-02-20 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Schweitzer Roy B → RACK SAND, INC.; 1985-02-20 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Schweitzer Roy B → Rack Sand Inc; 1985-02-20 to current/open; source msha-controller-operator-history