Continuing on from the mintmark moratorium that began in 1965, the U.S. Mint did not strike coins with any mintmarks in 1966. This, of course, included Kennedy half dollars, which in 1966 were still riding a high tide of popularity despite having no mintmarks and a paltry 40 percent silver composition (as opposed to the 90 percent silver makeup that it had in 1964).
Trying to stem the massive coin shortage that beset the country at the time, the United States Mint found itself in the position of striking 1964-dated half dollars late into 1965, and 1965 halves well into 1966. In fact, the first 1966-dated half dollars weren’t even minted until August 1, 1966! However, signs that the coin shortage was easing were already evident. Partly, this was due to the fact that hundreds of millions of copper-nickel clad coins were already in circulation and rapidly replacing the silver coins that had caused widespread hoarding pandemonium. Still, the Kennedy half dollar was not circulating, and thus the quarter was becoming the preeminent high-value coin.
In 1966, as in 1965, two types of Kennedy half dollars were available: the regular-strike 1966 Kennedy half dollar (of which 108,984,932 were made), and the 1966 Special Mint Set Kennedy half, which had a mintage of 2,261,583 pieces. Each is worth about $5 today.