The number one cause for the 60s was the election of JFK, a Nixon win in 1960 would have given the left much less to work with.
Having lived through the ‘60s, I understand the significance of JFK’s election, but was not the number one cause of the decade, but rather an effect. Demographics was the prime cause of the ‘60s. The huge Boomer generation was coming of age at the same time older people were anxious to move on from the age of Eisenhower and the greatest generation. I actually met Kennedy at a campaign rally he held at Montgomery Blair H.S. A little more than two years later, I was standing outside of the Bethesda Naval Hospital watching his body arrive in a grey ambulance.