# Relationship history for MSHA mine 2200675

Current hierarchy: **David L  Smith; Mary Smith  Crockett → Smith Bros. Gravel → Smith Bros 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Smith Bros. Gravel → Smith Bros Gravel; 1996-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Mary Smith  Crockett et al → Smith Bros Gravel; 1996-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Mary Smith  Crockett et al → Smith Bros. Gravel; 1996-03-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David L  Smith et al → Smith Bros. Gravel; 1996-03-01 to current/open; source msha-controller-operator-history