Based on numismatic information, it is essential to first clarify that the United States did not produce a Kennedy dollar coin in 1974. The coin in question is the Kennedy half dollar. The value of this piece is entirely dependent on its metallic composition and mint of origin, which is indicated by a mint mark.
Standard 1974 Kennedy half dollars produced for general circulation at the Philadelphia (no mint mark) and Denver ("D" mint mark) mints are not made of silver. These coins have a copper-nickel clad composition. Due to the vast number of these coins minted and their lack of precious metal content, a circulated 1974 or 1974-D Kennedy half dollar is typically worth only its face value of 50 cents. Even in uncirculated condition, its value remains quite modest, usually just a small premium over face value.
However, the San Francisco Mint produced special versions for collectors in 1974, which are identifiable by an "S" mint mark. These 1974-S Kennedy half dollars were struck in a 40% silver-clad composition. These are the only 1974-dated Kennedy half dollars that contain silver, and consequently, they are worth more than their face value. Their base value is tied to the melt value of their silver content, with an additional premium based on their numismatic desirability and condition. The exact worth of a 1974-S silver half dollar fluctuates with the spot price of silver but is generally several dollars.
