The five Panama–Pacific commemorative coins ($50 piece pictured) were produced in connection with the 1915 Panama–Pacific International Exposition in San Francisco. Struck at that city's mint, the issue included round and octagonal $50 pieces. Excepting modern bullion coins, these two gold pieces are the highest denomination ever issued and the largest coins ever struck by the United States Mint. The octagonal $50 piece is the only non-round U.S. coin ever issued. In January 1915, Congress passed legislation for a silver half dollar, as well as a gold dollar, a quarter eagle ($2.50 piece), and the two $50 pieces. The Mint had already consulted artists, but Treasury Secretary William G. McAdoo initially rejected all their designs. Two of them
