Quarter (United States coin) The quarter, short for quarter dollar, is a United States coin worth 25 cents, one-quarter of a dollar. It has a diameter of .955 inch (24.26 mm) and a thickness of .069 inch (1.75 mm). The coin sports the profile of George Washington on its obverse, and its reverse design has changed frequently. 1966 us silver quarter. Discussion in 'What's it Worth' started by justin i just came across a u s quarter dated 1966 in which i believe to be pure silver is this possible i thought silver quarters ended in 1964 if so how much is it worth it has no mint marking justin_case, Jul They did end silver content in quarters in 1964. The 1966 Special Mint Set (Buy on eBay) would contain the same line up of coins as the prior year, although the packaging would be modified. Each set contained the 1966-dated Kennedy Half Dollar, Washington Quarter, Roosevelt Dime, Jefferson Nickel, and Lincoln Cent.