The stars represent major historical events. Such as the great Chicago Fire of 1871, Worlds Columbian Exhibition, Century of Progress Exhibition, and Fort Dearborn. Just as the Chicago flag.
The Blue represents the bodies of water in Cook County such as The Chicago River and Lake Michigan.
The outline of Cook County is the borders of Cook County.
The blue and white also represents the amazing city that is in cook county Chicago.
The white is for the long winters.