The biggest is absolutely barbecue. Nothing else comes close.

Chicago vs New York.

I don't even gotta say the food.

Each region has different foods. The south loves their BBQ and there is roughly one style per state in the south (the Carolinas and Texas have multiples), and each is fiercely defended as the best. (Shout-out to Owensboro mutton!)

Hotdogs and how they are served are another fight. Chicago, NY, Seattle, etc. have distinct styles and are eaten enough at lunch that folks become very protective of their mid-day rituals.

Soda/pop/soft drink flavors are also weirdly regional.

And none of these factor in the folks in the underrepresented areas like Hawaii, Alaska, etc. I can't even find info on food preferences for PR, Samoa, Guam, etc. Actual fruit and pork are big flavors that get their own treatment but aren't acknowledged as American, like Kalua pork or Taxi soda.

American is like a bunch of different regions that share a currency. Each has its own unique perspective on food and drink.

Chili with or without kidney beans

Seasoning a steak with salt, pepper, both, or neither, also temps above medium-rare

A bunch already covered bbq's

Green bean casserole requires crispy fried onions on top

Ketchup on a hot dog or eggs can be pretty contested in the right crowd

Peanut butter on a hamburger

JFK was killed over preferring Carolina style BBQ over Texan.

Source: A Texan coworker told me.

Maryland crab cakes vs crab cakes from anywhere else

NM chile vs Colorado chile vs any other chili

Tex Mex vs CA Mex vs New Mexican vs Mexican

BBQ styles tend to get people picking sides because they vary so widely and often have something to then that is unfamiliar to people who are used to another style.

All involve slow cooking. Some are dry, as in dry spices and seasonings are applied but no moisture. Others are wet and are frequently slathered in sauce while cooking. Some have a very strong smokey flavor and some have a strong vinegar taste.

I like most types, except the ones with the strong vinegar flavor. While I won't tell someone they are wrong for liking that, if I accidently bite into the vinegar based BBQ it makes me angry and people being confrontational about it makes a bit more sense.

There is also some pizza rivalries and people who like Chicago deep dish are wrong.

I know here in NC, the biggest may be Eastern BBQ vs Western. And yes there most definitely is a right answer!

Another vote for barbecue. Also, the right answer is Texas. Barbecue, Tex-Mex, and Willie Nelson are about the only things keeping this place worth half a damn, and Willie's gettin' up there.

This is not to say (most of) the other types are not delicious. They're just not better. Specifically looking at YOU, sauce-dripping KC silliness. You're just Texas style but slightly worse.

Connecticut picked a fight over pizza and won.

Edit: the WELCOME TO THE PIZZA CAPITAL OF AMERICA signs on the highway point into New York, for added shit kicking. We put up different ones to gloat at Massachusetts and Rhode Island. Something about basketball for Springfield, because they have a basketball hall of fame. I don't fuck with Rhode Island or I-95 so I don't know what's out east.

Okra and tomatoes belong in gumbo