The 1919-D Lincoln Cent can be considered one of the semi key dates, as most early teens and twenties Lincoln Cents from the Denver and San Francisco Mints' are considered semi key dates also.
The 1919-D is however ,one of the more common dates from the Denver and San Francisco Mint from the early date coins in the series. Examples in MS63 and MS64 still exist in the hundreds. In MS65 condition, they become much scarcer but enough examples remain to keep prices affordable for most serious collectors. In MS66 condition it is very scarce, with less than a few dozen known. In MS67 condition or higher it is almost unheard of with the exception of 1 or so examples verified.