# Relationship history for MSHA mine 4003541

Current hierarchy: **David R  Byrd; Jamie Lee  Johnson → Houston Branch Sand & Gravel, LLC → Houston Branch Sand & Gravel Quarry #2**

- 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:** David R  Byrd et al → Houston Branch Sand & Gravel Quarry #2; 2019-03-04 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Houston Branch Sand & Gravel, LLC → Houston Branch Sand & Gravel Quarry #2; 2020-10-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David R  Byrd et al → Houston Branch Sand & Gravel, LLC; 2020-10-21 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Jamie Lee  Johnson et al → Houston Branch Sand & Gravel, LLC; 2020-10-21 to current/open; source msha-controller-operator-history