A lot of them were Northern union workers who turned on student demonstrators over their opposition to the Vietnam War and anti-communism in general, manifesting as the Hard Hat Riot of 1970 ("how
dare they oppose the expansion of this devestating war into neutral Cambodia!
Capitalist rubber stamp Friend of the workers George Meany says we should go beat up those peaceful protesters"). Maybe a good chunk of Southerners voted this way, but I wonder how much of that was a mirage caused by Wallace-Nixon voters.
Fun fact about the Hard Hat Riot: the construction workers involved were actually building the World Trade Center, famous for another historical event.