PCGS -
Jefferson nickels have been around since 1938, but despite the long run of this popular series, it has not spawned many truly rare dates among the regular issues. Only a handful of regular-issue business strikes saw mintages of less than 10 million pieces, but there two circulation issues saw relatively small mintages of fewer than 5 million apiece. These two issues, regarded as key-date coins for the series, have kept collectors busy searching through circulation since the middle of the 20th century. The two
Jefferson nickels that reign supreme as series key dates are the 1939-D and 1950-D.

Both coins hail from the Denver Mint, which by the middle of the 20th century had become one of the most prolific branch mints in terms of overall coin production. While branch mints historically struck smaller numbers of coins than the "mother" Philadelphia Mint, the Denver Mint saw productions of certain coins that easily rivaled - and sometimes exceeded - same-year output for particular issues from its counterpart facility in Philadelphia.
However, that wasn't the case in 1939 or 1950. The Denver Mint struck only 3,514,000 examples of the 1939
Jefferson nickel in 1939, making the 1939-D
Jefferson nickel the scarcest five-cent coin the Denver Mint had produced since it began striking the denomination in 1912. Even fewer
Jefferson nickels would be struck by the "Mile-High" Mint little more than a decade later, in 1950. That's when just 2,630,030 nickels rolled off Denver's presses - a number that still stands as the lowest-mintage regular-issue five-cent piece struck at the Denver Mint.
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