A nickel, in American usage, is a five-cent coin struck by the United States Mint. Composed of 75% copper and 25% nickel, the piece has been issued since 1866. Its diameter is .835 inches (21.21 mm) and its thickness is .077 inches (1.95 mm). Due to inflation, the purchasing power of the nickel continues to drop and currently the coin represents less than 1% of the federal hourly minimum wage. In 2015, over 1.5 billion nickels were produced at the Philadelphia and Denver mints.
The silver half dime, equal to five cents, had been issued since the 1790s. The American Civil War caused economic hardship, driving gold and silver from circulation; in response, in place of low-value coins, the government at first issued paper currency. In 1865, Congress abolished the five-cent fractional currency note after Spencer M. Clark, head of the Currency Bureau (today the Bureau of Engraving and Printing), placed his own portrait on the denomination. After the successful introduction of two-cent and three-cent pieces without precious metal, Congress also authorized a five-cent piece consisting of base metal; the Mint began striking this version in 1866.
The initial design of the Shield nickel was struck from 1866 until 1883, then was replaced by the Liberty Head nickel. The Buffalo nickel was introduced in 1913 as part of a drive to increase the beauty of American coinage; in 1938, the Jefferson nickel followed. In 2004 and 2005, special designs in honor of the bicentennial of the Lewis and Clark Expedition were issued. In 2006, the Mint reverted to using Jefferson nickel designer Felix Schlag's original reverse (or "tails" side), although a new obverse, by Jamie Franki, was substituted. As of the end of FY 2013, it cost more than nine cents to produce a nickel; the Mint is exploring the possibility of reducing cost by using less expensive metals.