# Relationship history for MSHA mine 4102924

Current hierarchy: **Birdwell Jerry & Bill Mc Millian → Birdwell Construction Company → Tarrant County Pits**

- 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:** Birdwell Construction Company → Tarrant County Pits; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Birdwell Jerry & Bill Mc Millian → Tarrant County Pits; 1979-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Birdwell Jerry & Bill Mc Millian → Birdwell Construction Company; 1979-01-01 to current/open; source msha-controller-operator-history