# Relationship history for MSHA mine 2200718

Current hierarchy: **Martha E Dobbs → Preston Dobbs Truck Service & Gravel Sales LLC → Preston Dobbs Truck Service & Gravel Sal**

- 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:** Preston Dobbs → Preston Dobbs Truck Service & Gravel Sal; 1999-02-01 to 2017-09-30; source msha-controller-operator-history
- **controller_controls_mine:** G Preston  Dobbs → Preston Dobbs Truck Service & Gravel Sal; 1999-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** G Preston  Dobbs → Preston Dobbs; 1999-02-01 to 2017-09-30; source msha-controller-operator-history
- **operator_operates_mine:** Preston Dobbs Truck Service & Gravel Sales LLC → Preston Dobbs Truck Service & Gravel Sal; 2017-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Martha E Dobbs → Preston Dobbs Truck Service & Gravel Sal; 2017-10-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Martha E Dobbs → Preston Dobbs Truck Service & Gravel Sales LLC; 2017-10-01 to current/open; source msha-controller-operator-history