I assume people aren't surprised to see Bruno Sammartino as #1. He was WWWF champion for a combined eleven years over two title reigns. That's a lot of main eventing in New York, Philadelphia, Boston, Washington D.C., Baltimore, and Pittsburgh.
#4
Antonino Rocca was the Italian-American hero in the northeast before Bruno was. That's why he's at #4. Rocca was big enough to make a cover of the Superman comic.
http://dc.wikia.com/wiki/Superman_Vol_1_155
Hogan and Backlund are #2 and #3 on the list and in combined WWF title reigns (separated by just 47 days). The nature of the WWF touring the northeast big arenas, especially during Backlund's reign, means they would accumulate big numbers.