This article more or less rings true:

http://tinyurl.com/ku5tae4

Having grown up in the epicenter of the pizza belt, I'm usually
disappointed by the pizza I've encountered outside of it. In all the
years I've lived in the Washington, D.C., area, I've only encountered
two restaurants that make pizza that even resembles the good stuff from
New Haven. And there was one pizza joint in NE Florida that had
satisfactory pizza...and it turns out the owner and chef was from
Providence.