Jonathan Zabulsky's, the Aramark- and private equity-backed website which claims to be the busiest online prepared-food takeout and delivery service in the US (it just absorbed MenuPages, after rival GrubHub bought born-in-Philly Dotmenu), says it's found big regional variations in what its 1.5 million monthly users order in.
Here's the Seamless list of "top cuisines by market":

  New York, Chicago, San Francisco - Delicatessen
    Los Angeles - American
      Washington DC - Soup and Sandwich
          Boston - Thai 

And in Philadelphia? "It's pizza,"  Danielle Orsino, spokeswoman for Seamless, told me. "Philadelphia is the only city in the top seven US metropolitan areas that prefers pizza over all other cuisines."

American pizza, we know, is still typically glopped with industrial yellow mozzarella cheese (or even American cheese, as in certain Irish bars in my old West Philly and Roxborough neighborhoods), a degenerate legacy of our large Southern Italian/Sicilian-American heritage, or what Time Magazine reviewer R.Z. Sheppard (re Elmore Leonard's novel Glitz) memorably called "the Philadelphia-South Jersey axis of ethnic indigestibles."

So what's with Boston and Thai food? Weird.