Pizza is pretty good... invented in NYC by Italian immigrants iirc, so technically American, although I gather there is controversy surrounding that take (flatbread was invented in Italy, even with cheese topping, but the whole tomato sauce thing that we recognize today was invented here; this orc entirely ignoring the debate about whether flatbread is "better" or "worse" than American style pizza).
Proper crab cakes. Unfortunately 99.9% of the country doesn't do it right, so you basically have to travel to very specific parts of Maryland to actually understand the hype.
In a similar spirit, the Juicy Lucy was invented in MN, though two different bars claim to be the ones that invented it.
A Jucy Lucy (or Juicy Lucy) is a stuffed cheeseburger with the cheese inside of the meat instead of on top, resulting in a melted core of cheese. It is a popular, regional cuisine in Minnesota, particularly in the Twin Cities of Minneapolis and Saint Paul. Two bars in Minneapolis claim to have invented the burger, while other local bars and restaurants have created their own interpretations of the style.
There's good ones, and there's the ones you can buy at the gas station, lol. If you're ever in the area, I can recommend some good ones.
A couple weeks ago a bunch of friends from college came in for a semi-annual get together. The ones from out of state were all craving pepperoni rolls. I begged them not to buy anything from a gas station / convenience store and to let me hook them up.
I showed up the next day with $100 worth of these super bougie artisanal rolls from a local place. They were a hit.