Public opinion has been shown to be largely reactionary, and so the events of the recent past influences people to lean one way or another.

In that vein, there are three events of note in North American history that centres around 1967.

The first was the torture, rape and murder of 8 student nurses, by Richard Bejamin Speck in 1966.

The second is the Shell Lake Mass Murder in 1967, where Victor Ernest Hoffman murdered 9 people, most of whom were sleeping, in a single event.

The third were the Michigan Murders, committed by John Norman Collins in 1967, who is believed to be responsible for 7 murders between 1967 and 1969, though he was only tried for a single murder.

My own thoughts on this, and this is just speculation on my part, is that the publicity as well as the public outcry for the 1966 murders, the young age of the victims, the nature of the crime, as well as the early time of year that it happened, accounted for the rise in support for the death penalty.