The quarter-dollar is 1/4 of a U.S. dollar, or 25 cents. This is one way in which American currency differs from a majority of other countries, who have a 20 cent denomination. The decision to go with a 25 cent came from the practice of dividing a Spanish Milled Dollar into 8, wedge shaped segments. Because of this at one time it was common to hear "two bits", two pieces of eight, as a nickname for the quarter.

The copper-nickel clad series of Washington Quarters started in 1965, and as part of the switch Denver and San Francisco didn't put their mint marks on from 1965 to 1967. This went for all denominations. The switch from silver to copper-nickel clad occurred because the federal government was losing money because the silver value of U.S. coins was worth more then their face value and were being melted down by individuals for profit. For the first three years of clad production, specimen sets were specially sold as "Special Mint Sets" minted at the San Francisco mint in 1965, 1966, and 1967. There are also coins in the set known as "Deep Cameo". These spectacular coins are highly valued because of their rarity).