Northern Florida is culturally Deep Southern, which is also why it voted for Wallace in 1968
That is definitely a part of it, but Goldwater even won places like Palm Beach and Broward (!!!) Counties.
Goldwater generally put up some of his best numbers in well-off/suburban/already Republican-leaning, Southern counties like those, which weren't quite what they are today. For example we hadn't quite seen the influx of Northeastern, disproportionately Jewish, people to South Florida yet. Among those who were already there, Goldwater being a man of Jewish descent probably didn't hurt him.
