Home>Choose State>Cities in Illinois>Institutions in Mackinaw>First Security Bank Locations in Mackinaw First Security Bank Branch Locations in Mackinaw, IL 1. First Security Bank - Mackinaw Branch 101 East Fast Street, Mackinaw, IL 61755 (309) 359-3961 View Branch 2. First Security Bank - Heritage Lake Branch #2 Bradford Drive, Mackinaw, IL 61755 View Branch