Mint Marks are small letters designating where the coins were minted. The Mint Mark position is usually found on the reverse of coins minted prior to 1965 (with the cent being the exception), and on the obverse after 1967.

Coins struck at the Philadelphia mint before 1979 (except 1942-1945 five-cent pieces) do not have a mint mark. Starting in 1979 a letter P was used on the dollar, and on all other denominations except the cent thereafter.

All Dies for United States coins are made at the Philadelphia Mint and are stamped with the appropriate mint mark before they are shipped to the branch mints. The exact positioning and size of the mint mark may vary slightly, depending on where and how deeply the punch was impressed.