# Relationship history for MSHA mine 2200579

Current hierarchy: **Michael A  Bush → Bush Construction Co., Inc. → Richton Sand And Gravel**

- 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

- **controller_controls_mine:** Patricia  Hughes  et al → Richton Sand And Gravel; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Michael A  Bush  et al → Richton Sand And Gravel; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** American Sand & Gravel Company → Richton Sand And Gravel; 1986-06-01 to 1995-10-31; source msha-controller-operator-history
- **controller_controls_operator:** Patricia  Hughes  et al → American Sand & Gravel Company; 1986-06-01 to 1995-10-31; source msha-controller-operator-history
- **operator_operates_mine:** Bush Construction Co., Inc. → Richton Sand And Gravel; 1995-11-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael A  Bush  et al → Bush Construction Co., Inc.; 1995-11-01 to current/open; source msha-controller-operator-history