December 1963 was still for the most part not much different than the 1950s. Most of the defining events of the 1960s decade was still in the future in December of 1963. JFK had just been murdered but The Beatles hadn't even hit US radio yet and Vietnam was still a minor conflict half a world away.
Ditto for December 1973, and so on.
True. The early ‘60s were like the ‘50s in many ways.
Remember how we used to hear about the ‘60s, the ‘70s, the 80s, etc. I have hardly heard anyone talk of decades since the turn of the century.
Does anyone ever talk about the ‘00s, or the ‘10s?
I remember someone talking about “American Graffiti” as being a depiction of the ‘50s, yet the events in that movie were said to have happened in 1962.