# Relationship history for MSHA mine 1800293

Current hierarchy: **A H  Smith Jr; Henry R  Smith → A H Smith Associates Limited Partnership → Davis Sand & 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Davis Sand & Gravel Corp → Davis Sand & Gravel; 1950-01-01 to 1988-11-22; source msha-controller-operator-history
- **controller_controls_mine:** A H  Smith → Davis Sand & Gravel; 1950-01-01 to 1988-11-22; source msha-controller-operator-history
- **controller_controls_operator:** A H  Smith → Davis Sand & Gravel Corp; 1950-01-01 to 1988-11-22; source msha-controller-operator-history
- **operator_operates_mine:** A H Smith Associates Limited Partnership → Davis Sand & Gravel; 1988-11-23 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** A H  Smith Jr et al → Davis Sand & Gravel; 1988-11-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** A H  Smith Jr et al → A H Smith Associates Limited Partnership; 1988-11-23 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Henry R  Smith et al → A H Smith Associates Limited Partnership; 1988-11-23 to current/open; source msha-controller-operator-history