Mint marks are small letters that indicate where a coin was manufactured ("struck"). The mint mark location is often on the backs of coins dated 1964 and earlier - but not always. As of 1968 the position was standardized on the front of all circulating coins.
Possible letters are:
- Blank = Philadelphia, up to 1979 on nickels and higher denomination coins, and all Philadelphia cents.
- P = Philadelphia, 1980-present on nickels and higher denomination coins, 1979 dollars, and "war nickels" minted during WWII
- D = Denver, 1906-present
- S = San Francisco
- W = West Point (bullion coins only, 1980's to the present)
- O = New Orleans (up to 1909)
- CC = Carson City (1870-1893)
- D = Dahlonega, GA (gold coins only, 1838-61)
- C = Charlotte (gold coins only, 1838-61)
