St. Louis-style pizza is a variant of Chicago-style thin crust that is popular around St. Louis, Missouri and southern Illinois. The most notable characteristic of St. Louis-style pizza is the distinctive Provel cheese used instead of (or rarely in addition to) the mozzarella common to Chicago-style thin crust. The toppings are usually sliced instead of diced. If ordered with sausage or hamburger, the meat is squeezed off by hand into marble-sized chunks. The crust is thin enough that it becomes very crunchy in the oven and is sometimes compared to a cracker. Even though the crust is round, it is always cut into small squares.
Greek pizza is a variation popular in New England; its name comes from it being typical of the style of pizzerias owned by Greek immigrants. It has a thicker, chewier crust and is baked in a pan in the pizza oven, instead of directly on the bricks. Plain olive oil is a common part of the topping, as well as being liberally used to grease the pans and crisp the crust. Variations in other parts of the country include using feta cheese, Kalamata olives, and Greek herbs such as oregano.
Hawaiian pizza has Canadian bacon (or sliced ham) and/or bacon with pineapple toppings with Mozzarella cheese. This type of pizza is especially popular in the western United States, and is also a popular topping combination in Australia, Canada, and Sweden, but notably not in Hawaii. This type is also common within the EU, where it is known as pizza Hawaii.
New Haven-style pizza, also known as apizza, is popular in Connecticut. It has a thin crust that varies between chewy and tender, depending on the particular establishment. The default version is a "white" pizza topped with only garlic and hard cheeses; customers who want tomato sauce or mozzarella cheese have to ask for them explicitly. Apizza has a very dark, "scorched" crisp crust that offers a distinctive bitter flavor, which can be offset by the sweetness of tomatoes or other toppings. New Haven-style pizza is traditionally cooked in brick ovens.