# Relationship history for MSHA mine 2000794

Current hierarchy: **Edward C  Levy Jr → Milford Sand & Gravel Company → MILFORD-WALKER**

- 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:** Medusa Aggregates Company → MILFORD-WALKER; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Medusa Corp → MILFORD-WALKER; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Medusa Corp → Medusa Aggregates Company; 1950-01-01 to 1978-12-31; source msha-controller-operator-history
- **controller_controls_mine:** Crane Company → MILFORD-WALKER; 1978-12-13 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Medusa Aggregates Company → MILFORD-WALKER; 1979-01-01 to 1982-12-09; source msha-controller-operator-history
- **controller_controls_operator:** Crane Company → Medusa Aggregates Company; 1979-01-01 to 1982-12-09; source msha-controller-operator-history
- **operator_operates_mine:** Milford Sand & Gravel Company → MILFORD-WALKER; 1982-12-10 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Edward C  Levy Jr et al → MILFORD-WALKER; 1983-12-10 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Edward C  Levy Jr et al → Milford Sand & Gravel Company; 1983-12-10 to current/open; source msha-controller-operator-history