# Relationship history for MSHA mine 4503386

Current hierarchy: **Patricia  McKay; Michael  McKay → Island Concrete Products → PORTABLE CRUSHER #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:** Island Concrete Products → PORTABLE CRUSHER #1; 1999-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_mine:** Michael  McKay et al → PORTABLE CRUSHER #1; 1999-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Michael  McKay et al → Island Concrete Products; 1999-02-01 to current/open; source msha-controller-operator-history
- **controller_controls_operator:** Patricia  McKay et al → Island Concrete Products; 1999-02-01 to current/open; source msha-controller-operator-history