Look in a roll of nickels and the odds are that you will find a 1964 nickel.

During the ‘The great coin shortage of the '60s’ the U.S. Mint was working overtime to meet the demand for new coins. But the amount needed was far more than the mint could produce. In the calendar year of 1964 of mint only produce a small number of nickels. Fear that the same fate would befall them that befell the 1950D nickels. On 9/3/64 the mint was authorized to freeze the date on nickels, and continue to make them in 1965 and in the end the mint produced:

1964 – 1,024,672,000
1964D – 1,787,297,160