What was the last minted quarter made of silver?

The last minted quarter made of silver was produced by the U.S. Mint in 1966 in accordance with the Coinage Act of 1965. The first clad quarters, containing no silver, were minted in August 1965.

Prior to the passage of the Coinage Act of 1965, the mint made quarters out of 90 percent silver and 10 percent copper. After the law's passage, the Mint switched to a combination of 92 percent copper and 8 percent nickel. Starting in 2010, the Mint began using an America the Beautiful design, expected to be in use until 2021. From 1999 to 2008, the mint used a Washington statehood design.