肯尼迪半美元
The new tradition of placing past presidents and Founding Fathers on coins, which had begun with the 1909 Lincoln cent, continued in the 1930s and 1940s, with the introduction of the Washington quarter in 1932, the Jefferson nickel in 1938, the Roosevelt dime in 1946, and the Franklin half dollar in 1948. The original Washington quarter design remained unchanged, aside from the removal of silver content and finer details, up to 1998, the Jefferson nickel up to 2003, and the Roosevelt dime to the present day. The Franklin half was replaced by the John F. Kennedy half dollar in 1964 to commemorate him after his murder. The composition of the Kennedy half dollar was changed from 90% silver to 40% silver in 1965 and remained that way through 1970. After 1970, Kennedy half dollars were made of the same copper-nickel alloy as the other denominations.