The terminal date for United States circulating half-dollar coins composed of 90% silver occurred in 1964. These coins, primarily the Kennedy half-dollar released mid-year, represented the last issue of this denomination with such a high silver content intended for general circulation.
The discontinuation of silver in circulating coinage reflects a significant shift in monetary policy driven by increasing silver prices. The intrinsic value of the silver content in these coins began to exceed their face value, incentivizing melting and hoarding. The removal of silver aimed to stabilize the coinage system and prevent the disappearance of currency from circulation.