# Relationship history for MSHA mine 2300248

Current hierarchy: **David K  Willard → Willard Quarries Inc → BUCKHORN PLANT # 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: 2026-10-13T11:19:05.459773+00:00

## Valid-time edges

- **operator_operates_mine:** Howard Quarries Inc → BUCKHORN PLANT # 2; 1950-01-01 to 1988-10-16; source msha-controller-operator-history
- **controller_controls_mine:** Howard Olen → BUCKHORN PLANT # 2; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Howard Olen → Howard Quarries Inc; 1950-01-01 to 1988-10-16; source msha-controller-operator-history
- **controller_controls_mine:** David K  Willard et al → BUCKHORN PLANT # 2; 1950-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Willard Quarries Inc → BUCKHORN PLANT # 2; 1988-10-17 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** David K  Willard et al → Willard Quarries Inc; 1988-10-17 to current/open; source msha-controller-operator-history