What is a “key date” coin? Specifically, it is a coin which is scarce for a series of coins.
A “series” of coins refers to an entire run of a particular kind of coin. For example, the series of Wheat cents would include every cent that the U.S. Mint created. It includes every year and mint mark that the mint created those cents for. The key dates for that series are the ones that are hard to get. You may also hear these coins referred to as “tough date” coins.
The term “key date” is not a precise name for these coins. Often, it’s not just the date, but the DATE and MINT MARK that is considered scarce. In some years, a coin would be minted in abundance in one mint but in another mint only a few were made. In that case only the coin with the year and mint mark from the second mint could qualify as a key date coin.
A “semi key date” or “semi key” refers to a coin which can be difficult to acquire but are not as scarce as a true key date coin.
For example, let’s look at the Mercury dime. Mercury dimes were minted in abundance from 1916 to 1945 but there are only a few that are considered key date or semi key date coins.
Mercury Dimes
- 1916-D
- 1921 (semi)
- 1921-D (semi)
1916-D Mercury dime is considered a key date coin. They had a very low mintage from the Denver mint that year. Those minted in Philadelphia were minted in abundance and are not considered key date coins. The 1921 and 1921-D Mercury dime had a low mintage. But, their mintage was much higher than the 1916-D. Therefore, they can be called semi key date.
To help you in your search for key date coins, I listed some popular coins and their key dates. Note that some of them have peculiar names. The best thing to do is look them up and see what the name is describing. The Buffalo nickel “Three Legged Buffalo” is a good example. If you look at a picture of it, you can see it’s a mint error which makes it look like there’s an additional leg on the buffalo. There are many references below in the Reference section where examples of these coins can be seen.
Wheat Cents
- 1909-S VDB
- 1909-S
- 1910-S (semi)
- 1911-S (semi)
- 1912-S (semi)
- 1913-S (semi)
- 1914-S (semi)
- 1914-D
- 1915-S (semi)
- 1922 No “D” (No Mint Mark)
- 1931-S
Buffalo Nickels
- 1913-S Type 2
- 1921-S (semi)
- 1924-S (semi)
- 1926-S (semi)
- 1937-D Three Legged Buffalo
Kennedy Half Dollars
- 1970-D (semi)
- 1998-S Matte Finish
Morgan Dollars
- 1881 CC
- 1885 CC
- 1889 CC
- 1893 CC
- 1893 S
- 1895 Proof
- 1895 S