The 1921-D Mercury dime, like its Philadelphia-mint counterpart, is a very scarce semi-key coin in all grades. It has the second-lowest mintage in the series, behind only the elusive 1916-D Mercury dime. While the mintage for this piece is above 1 million, only a small fraction of these coins survived in collectible grades.

The 1921-D is particularly scarce in higher-end grades of XF40 or better and is rare in uncirculated condition. Gems are especially elusive, with perhaps only a few dozen pieces available in MS65 or better. In MS67 or higher, the 1921-D becomes one of the top rarities of the entire series.

Why are 1921-D Mercury dimes so tough? For one, there’s the coin’s low mintage. A mild recession along with the US Mint’s production prioritization going to striking 1921 silver dollars, helped to keep this issue and most others from 1921 relatively low. Still, not many collectors were saving branch-mint coins in the teens and 20s. This owes to in part why so many D- and S-mint coins of this era are nearly impossible to find in the high grades. Date-and-mintmark collecting did not become en vogue until the 1930s and ‘40s, and by then most pieces like the 1921-D Mercury dime were already lost or worn beyond collectability.