This was principally commercial issue, sold by concessionaires at each end of bridge; struck in considerable quantity but most were pierced and attached to key chains.
Photos courtesy of John Dean
Obv. Bridge superimposed over outline of Michigan with five-pointed star marking Mackinac Straits; to lower l. Mackinac / Bridge / 1958
Rev. Male bust facing l.; to l. Built by the / Will of a Great / People Upon / Foundations of / Michigan's Faith / in Her Future / (signed) G. Mennen Williams / Governor
HK-709 Gilt. 33mm.