1964 was the first year the Kennedy Half Dollar was minted and the only year it contained 90% silver. The decision to mint the coin in 90% silver was in remembrance and tribute to a beloved President that was taken away too soon due to being assassinated Nov 22nd, 1963. 1965 to 1970 the coin was minted with 40% silver and after that (with the exception of some select special releases and proof coins) the Kennedy Half Dollar no longer contained any silver. This history and its 90% silver content is why this is a favorite among collectors and pretty much never found in circulation or in bank rolls. People here in the states and abroad started hoarding these coins from the onset on their release.