I went to college in New York from 1968-72. The drinking age was eighteen (as far as I know, it was
never 21, certainly not in my lifetime). I drove across the country in 1969-70 and drank legally in every state except Utah.
I stongly doubt your version of the facts.
New York's drinking age was 18 at least in the late 50s and early 60s. If it was ever 21, before Congress threatened the states with the loss of federal highway funds, I am not aware of it.
Regards,