Philadelphia has many things it can call its own. There's Wawa, the Cadillac of Convenience Stores. Tasty Kakes, similar to Hostess. And then there's the Mummers Parade, which, from an outsiders perspective, is a New Years day event where groups of grown men (likely still drunk from the prior nights festivities), called Fancy Brigades, put on crazy outfits and dance around for two minutes in the streets. I think it's pretty ridiculous, but so as not to offend any of our Philly native friends, I'm providing a link to a full explanation here: http://en.wikipedia.org/wiki/Mummers_Parade.
You can find Wawa in other East Coast states and the same goes for Tasty Kakes. And I think you can see the Mummer's Parade on national television even, if you really look. But as far as I can tell, Scrapple is truly unique to Philadelphia. Scrapple is a meat, of sorts, similar to Spam. Historically, it was literally the meat "scraps" from breakfast all mushed together into a brick, sliced like bread, and cooked on a frying pan. I received such a brick as a white elephant gift this year and cooked some up. Below are the before and after pictures. In the end, when sliced thin, it wasn't too bad. I think I can officially call myself a true Philadelphian.