what year was the kennedy half dollar 40 silver

[LaJosephine]

Based on the provided information and numismatic history, Kennedy Half Dollars with a 40% silver composition were produced for circulation from 1965 through 1970.

The search results indicate that the Kennedy Half Dollar program went through distinct changes in its metal composition. The first year of issue, 1964, was the only year these coins were struck with 90% silver for general circulation. Following 1964, the U.S. Mint reduced the precious metal content, leading to the 40% silver versions issued between 1965 and 1970. After this period, the silver content was eliminated from circulating Kennedy half dollars.