Numismatists (coin collectors) likely have a few half dollars stashed away in their collection. Since 2002, the half dollar has only been minted for collection purposes. This was due to a large inventory and lack of demand. These coins are no accepted in vending machines, slot machines, or other coin operated machines. Once supply levels of the coin drop, more will be minted. If you were lucky enough to find one in circulation you probably held onto it. Many magicians prefer the half dollar due to the coins weight and size.
During their prime, half dollars were used quite often. Many casinos accepted them, especially for games requiring a 50 cent ante like blackjack. The rise of silver in the 1960s caused a problem for the US Mint. The price of silver would have exceeded the value of the coins (dimes and quarters). In 1965, the composition of the coin changed to copper and cupro-nickel. The Kennedy half dollar, though, still contained silver. The percentage of silver in this 50 cent piece dropped from 90% to 40%.
Rise of the Quarter
As silver continued to rise, many people hoarded half dollars containing 90% silver. A roll of these coins would net around 7 ounces of silver. Eventually there were so few in circulation that businesses became used to it. The quarter soon became the highest value coin. Soon enough, banks and cash drawers stopped stocking the half dollar. Coin operated machines like payphones and vending machines did not make slots big enough to accept half dollars.
Half Dollars Today
Today the half dollar is virtually out of circulation. You would be hard pressed to find a place that accepted them or that issued them. It is mainly for the collector that the coin has been minted. If you have an interest in coins, the U.S. mint allows you to purchase modern day half dollars.