An entire nation went stand still in horror on November 22nd 1963 after a devastating incident; the assassination of the youngest U.S. president, John Fitzgerald Kennedy. JFK as he is popularly called is known for being an impetus for economic growth and prosperity, abolishing death penalty in the District of Colombia, the sanctioning of budget for Apollo 11 mission, and most importantly the end of state-sanctioned racial discrimination which he mentioned ‘…disturbs the national conscience, and subjects us to the charge of world opinion that our democracy is not equal to the high promise of our heritage’. 
To assuage the heart ache caused by the loss and to honor one of the most loved Presidents of the U.S.A, Congress authorized a new coin to be released in 1964. Mint director Eva Adams called Chief Engraver Gilroy Roberts within hours of the assassination to get a coin ready in honor of the late President. 
Kennedy Half Dollar – Design and Release
With very little time at hand, Gilroy Roberts reused the existing bust of JFK he had created for the Kennedy Medal of the Presidential series for the obverse. The reverse was designed by Frank Gasparro who reused his Kennedy Appreciation medal reverse design for the Half Dollar.
When the Kennedy Halvies (as they are sometimes called!) were released they became instantly popular both in the U.S and overseas. To meet the exponentially growing demand, the mint kept increasing the production until it had released almost 430 million of them. But the strangest phenomenon was that these Half Dollars were never seen in circulation. Almost all of them were hoarded by the public or coin dealers.
Kennedy Half Dollar – Key Dates
The 1964 Kennedy Half Dollar saw two versions; the regular and the ‘accented hair’ variety. The ‘accented hair’ variety came about because of Jacqueline Kennedy's dislike of the details of JFK’s hair above the ear. Only 40,000 to 1,20,000 coins of the ‘accented hair’ variety were sold and they trade at a premium.
The 1970-D Kennedy Half Dollar is considered a key date to the series as only 2,150,000 coins were minted. The 1970-D coins were not meant for circulation and because of their rarity, MS65 and above graded coins command a premium.
The 1976 Bicentennial Kennedy Half Dollar was part of the Bicentennial celebrations of American Independence. They were only included in the Silver Proof set and Uncirculated set of the year. This Kennedy Half Dollar had a new reverse design by Seth G. Huntington, depicting the ‘Independence hall’ and the words ‘200 years of Freedom’.
In 1998, the Kennedy collector set was released with a low mintage (only 62,000!) special matte finish coin. It was available to order only for a period of six weeks. The matte finish was obtained by using a special sand blasting technique involving glass beads and Aluminium oxide. A hard chrome plate was added for hardness and lubricity. 
In 2014, 3 coin sets were released to celebrate the 50th Anniversary of the Kennedy Half Dollars, a Gold Proof coin from the West Point mint, the Uncirculated coin set minted in Philadelphia and Denver and the Silver coin set with 4 coins from different mints (West Point, San Francisco, Philadelphia and Denver) with different finishes. All three sets had great demand and sell for a premium now.
The Kennedy Half Dollar was bound to become hugely popular owing to its history, albeit a sad one. Yet, even the mint wouldn't have anticipated the demand and the mysterious disappearance of the coins from circulation. There are still billions of Kennedy Half Dollars hidden somewhere across the country and it sparks theories even wilder than JFK's assassination conspiracy theories!