#16 - Cheesesteak
Country of origin: USA 
Thinly sliced steak and melted cheese in a hoagie roll, with additional toppings often including peppers, onions, and mushrooms, also known as a Philadelphia or Philly cheesesteak.
I imagine some may have this number 1
. This ranking assumes the provolone variety. Take your whiz to the fake cheese thread.
As somebody from out that way, no to all the bold.
Sliced/chopped ribeye, sharp American cheese* or wiz, grilled onions. No peppers or mushrooms and it's just called a "cheesesteak." Other parts of the country have stupidly added stuff and add "Philly" to the title.
*Despite my horror at American cheese being the top-ranked cheese, Cooper and Land O'Lakes make a very nice sharp American cheese that is ideal for cheesesteaks because it melts great into the steak.
ETA: As much as I love them, and my rankings had them ranked a lot higher, I'm okay with a 16 ranking because the variations across the country as an aggregate don't make this a top sandwich (just a few places in and around Philly do).