What is the rarest quarter?

The rarest quarter in the US is the 1894-S Barber quarter. Only 24 of these quarters are known to exist, making it highly coveted by collectors. The 1894-S Barber quarter was struck at the San Francisco Mint and is especially rare because only 392,000 were produced that year. Many of the 1894-S Barber quarters were melted down as a result of the Coinage Act of 1894, which required the government to purchase large amounts of silver and issue new coins. The few remaining 1894-S Barber quarters are worth millions of dollars at auction.