In 1911, production of Dimes at the Denver Mint facility jumped to an unprecedented level of over 11 million coins. This was a more than three-fold increase over the previous year and was close to the all-time high output of Barber Dimes at Denver. The reason for this big increase is unknown, but it may have simply been to place more Dimes into circulation in the western states.
This big mintage makes the 1911-D Dime one of the more common dates in the series. It is not as plentiful as the 1911-(P), but collectors will have no problem finding a Mint State example in all grades up to, and including, MS66. The best 1911-D Dime is a single PCGS MS67+.