In 1975 and 1976, Kennedy half dollars were partially revamped with 1776-1976 dual dating on the obverse and a depiction of Independence Hall on the reverse to celebrate the nation's bicentennial. A small number of proof bicentennial half dollars were minted in 40% silver. Otherwise, all Kennedy half dollars were minted in copper-nickel clad until 1992, when 90% silver proofs were reintroduced as an option for collectors.
The scarcest proof Kennedy half dollars are those with varieties, such as the 1964 Heavily Accented Hair half dollar. Cameo and deep cameo proof Kennedy half dollars from the 1960s and early 1970s are also scarce and command solid premiums over prices for typical Kennedy half dollars of the era. In 2014, the West Point Mint struck a one-year-only gold proof Kennedy half dollar in honor of the 50th anniversary of the beloved coin series. These generally trade for a small but healthy markup over spot prices.