Inspired by this thread, I’ve decided to start an opposite one. What foods are common in your area, but relatively rare elsewhere?
I’ll start with the area I grew up in, Rhode Island:
Frozen lemonade
Coffee milk
Pizza strips
New York System weiners
Dynamites
I live in New Jersey now but don’t really know any foods unique to here. I’m sure someone will enlighten me though! 
For Washington DC, I can only think of mumbo sauce.
Northern Ohio is perhaps the home of sauerkraut balls. 'course, these days they’re probably available nationwide. That wouldn’t have been the case 20-40 years ago.
I’ve traced them back to the early 1950s in Cleveland. I’m of the opinion that they became mostly popular there before coming to Akron.
Freihofer’s Chocolate Chip cookies. The best in the world.
I’ve never found an Italian beef that is anything close to what you get other than here in Chicago.
Our deep dish pizza is also unheard of outside the area.
The exceptions to this are invariably Chicago themed places or outposts of Chicago franchises such as Carmens, Al’s Beef, Portillos, Pizzeria Uno/Due, and Lou Malnatis.
Even so, the outposts just don’t measure up to the home grown places.
Here in Montana, there’s nothing you can’t get elsewhere, but the beef around here is far better than what you get in most of the country.
In my hometown of Cleveland, though, I’ll add stadium mustard. It’s called that because it got its start being served at Cleveland Municipal Stadium, and it is God’s own gift to hot dogs and sausage. I stock up on a few bottles every year when I come home.
And while sauerkraut balls might have been popular in Cleveland in the 50s, this is the first I’ve ever heard of them.
Eastern North Carolina barbecue
South Carolina barbecue (a.k.a. “Piggy Park”)
Brats!
Had a college roommate from Upper Nyack, NY
(who would wake us up at 2am to sing his high school song, but that’s a tale for which the public is not yet ready…)
He’d never been west of NY, so when he visited Wauwatosa, WI, we fed him Good Midwesterner Fare: German microbrews, corn on the cob, potato salad, Sun-Drop Cola (think crispy Mtn Dew)… and three different brands of bratwurst.
For years afterwards he’d see me across a crowded party and yell “Hey, D! What were those things you fed me again? Brats-wursts? Yeah! They were THE BEST!”
Chicken wings are now famous throughout the country. But beef on weck and spiedies are still pretty regional. A garbage plate is more a method of serving rather than anything unique in terms of food.
Toasted Ravioli for St. Louis.
How long has DC had mumbo sauce? When I first started traveling to different ghettoes in big cities in the U.S., I lamented the lack of a good Boss Sauce type sauce.
Detroit, Chicago, Boston, Philly, DC…anytime I asked for Boss Sauce, I got a blank stare. When I tried to explain it, they would say, “You mean something like a sweet and sour sauce?” “No, no, no. Not like that.”
This last trip to DC surprised me though. I went to a little soul food place and decided to try again. Success! She offered me mumbo sauce, and she spoke of it as if DC had this delicious sweet sauce all along! But I always ask when I go and had only gotten blank stares in response.
Anyways, it’s not as good as Boss Sauce. Or Country Sweetsauce either.
More Chicago-centric dishes:
Jibarito sandwiches (a Puerto Rican-American cheesesteak sandwich between fried plantains)
Tamales (a cornmeal tamale wrapped in paper and stuffed with spiced beef, similar to a Mississippi corn roll tamale, but dissimilar from Latin American types.)
Mother-in-law sandwich and its cousin the Humdinger (tamale on a bun with chile for the former, same with cheese for the latter. Mother-in-law can also be something also known as a “chili tamale”–a bowl of soupy chili with a Chicago tamale tossed in.)
And while we’re on Maxwell Street, there the bone-in pork chop sandwich also popularized by those stands.
In addition the Italian beef mentioned by MikeG, there’s it gluttonous sibling, the Italian beef combo, or simply “combo”, an Italian beef sandwich with an Italian sausage in it.
Rib tips and hot links This is the hallmark of South and West Side Chicago style barbecue. The old school places still make their barbecue in an aquarium smoker, which is pretty much unique to the Chicago area. The only place I’ve seen that type of smoker outside Chicago was at Cozy Corner in Memphis. Chicago-style hot links are different than Texas style, and rib tips are much more popular a barbecue item here than anywhere I’ve seen.
I had those at a restaurant in Santa Cruz. Don’t know if it’s still in business.
The only places I’ve seen those outside Ohio are both in Wisconsin: at Mader’s in Milwaukee and Mark’s East Side in Appleton.
Rochester is known for white hots.
Go farther down into the Finger Lakes and you’ll see grape pies, especially in Naples, NY.
Half the fast food franchises now are touting frozen lemonade. That must have escaped into the wild.
Lutefisk and lefse
Jucy Lucy (a hamburger with melted cheese in the middle)
Pearson’s Nut Goodie
Buffalo wings.
Frappes and jimmies. Someone should really start a thread about them!
Cudighi, a local version of Italian Sausage, but so much more.
And, of course, Pasties. Pronounced Paaaahsty, not Paste-y.
Both of these are so ubiquitous that I didn’t realize until I moved away that they weren’t staples everywhere.
And less well-known, local blueberries. They are very different than what are called blueberries in most of the US - they’re much smaller, much tarter, and more flavorful. And while I’m thinking berries, Thimbleberries. I don’t think I’ve ever seen them anywhere else, though the wiki article says they grow a lot of places. They’re weeds up here, found along the sides of the road. Bigger, tarter, and softer than raspberries.
