1975 United States Proof Set, 5 Coins Inside!!. 1975-S Proof Sets had collectors scratching their heads, asking ...

1975 United States Proof Set, 5 Coins Inside!!. 1975-S Proof Sets had collectors scratching their heads, asking "Why are the Dollar, Half Dollar, Quarter coins dated 1976?" In preparation for America's 200th Birthday, the U.S. Mints began producing Bicentennial Quarters, Half Dollars, and Dollars in 1975 that were dated 1976. Proof versions of these patriotic designs were included in 1975 Proof Sets, helping to boost sales by over 200,000 units.Each set contained six coins: One example each of the Lincoln Cent, Jefferson Nickel, Roosevelt Dime, Bicentennial Washington Quarter (Copper-Nickel Clad), Bicentennial Kennedy Half Dollar (Copper-Nickel Clad), and Bicentennial Eisenhower Dollar (Copper-Nickel Clad).About the sets: 1975-S Proof Coins are found with Brilliant, Cameo, and Deep Cameo surfaces. All three finishes are readily available.Mintage: 2,845,450 setsAn unknown (but extremely small) number of Proof 1975-S Dimes were struck without a mintmark. Although Proof coins were being struck at the San Francisco Mint at the time, the Philadelphia Mint was responsible for making the Proof dies (and adding the mintmark). Apparently, at least one die was sent from Philadelphia without the mintmark, and a small number of "S"-less Dimes were struck and released before the error was discovered. The 1975 "S"-less Dimes are so rare that they were not even discovered until 1978, when two examples surfaced. They may, in fact, be one of the rarest coins of the 20th century!