# Relationship history for MSHA mine 4801442

Current hierarchy: **Peter Kiewit Sons' Inc → Guernsey Stone & Construction Company → Portable Crusher 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: 2026-10-17T05:35:58.500035+00:00

## Valid-time edges

- **controller_controls_mine:** Peter Kiewit Sons' Inc → Portable Crusher No 1; 1979-01-01 to current/open; source msha-controller-operator-history
- **operator_operates_mine:** Guernsey Stone & Construction Company → Portable Crusher No 1; 1985-09-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Peter Kiewit Sons' Inc → Guernsey Stone & Construction Company; 1985-09-01 to current/open; source msha-controller-operator-history