FIRST DAY OF ISSUE  MACKINAC STRAITS BRIDGE 3-cent Stamp Block, Commemorating the Opening of the Mackinac Straits Bridgewith Illustration of the Mackinac Bridge Issued at Mackinac Bridge, Mich, Jun 25, 1958. FDC U.S. 3-cent stamp Commemorating the Opening of the Mackinac Straits Bridge. Block of 4 stamps. Postmarked Mackinac Bridge, Mich, Jun 25, 1958 Please shop our ever expanding store! Be sure to add us to your favorites list! Thank you. Powered by Turbo Lister The free listing tool. List your items fast and easy and manage your active items.