# Relationship history for MSHA mine 0300880

Current hierarchy: **Avant B L → Avant Gravel Company → Plant & Pit No 1**

- 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:** E L Smith → Plant & Pit No 1; 1950-01-01 to 1980-11-05; source msha-controller-operator-history
- **controller_controls_mine:** E L  Smith → Plant & Pit No 1; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** E L  Smith → E L Smith; 1950-01-01 to 1980-11-05; source msha-controller-operator-history
- **operator_operates_mine:** Avant Gravel Company → Plant & Pit No 1; 1980-11-06 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Avant B L → Plant & Pit No 1; 1980-11-06 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Avant B L → Avant Gravel Company; 1980-11-06 to current/open; source msha-controller-operator-history