The smallest American coin is the DIME, which has a diameter of 17.91 millimeters and a thickness of 1.35 millimeters. It is composed of 91.67% copper and 8.33% nickel. The DIME was first introduced in 1796 and is the only coin to have been issued by the United States government for circulation since the beginning of the nation. It is also the only coin to have been minted continuously since its introduction.