# Relationship history for MSHA mine 0200993

Current hierarchy: **Peter Kiewit Sons' Inc → Union Rock & Materials Corp → 59th Avenue Plant**

- Valid-time bounds: inclusive, date granularity
- Null end: open-ended in the upstream history row; not independent proof of present control
- Transaction-time observation: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **operator_operates_mine:** Union Rock & Materials Corp → 59th Avenue Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Peter Kiewit Sons' Inc → 59th Avenue Plant; 1950-01-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Peter Kiewit Sons' Inc → Union Rock & Materials Corp; 1950-01-01 to current/open; source msha-controller-operator-history