California-style pizza refers to pizza with non-traditional ingredients, especially those that use a considerable amount of fresh produce. A Thai-inspired chicken pizza with peanut sauce, bean sprouts, and shaved carrots is a popular variant in California-style pizza restaurants, as are taco pizzas, and pizzas that use chicken and barbecue sauce as toppings.
Chicago-style pizza, or Chicago-style deep-dish pizza, contains a crust which is formed up the sides of a deep-dish pan. It reverses the order of some ingredients, using crust, cheese, filling, then sauce on top. Some versions (usually referred to as stuffed) have two layers of crust with the sauce on top. The invention of deep-dish pizza occurred in America and transcends a single ethnic origin. Deep-dish pizza was invented by Ike Sewell and Ric Riccardo and first served in 1943 at Pizzeria Uno, which is still operating along with its twin restaurant, Pizzeria Due, in the River North neighborhood.
Chicago-style thin-crust pizza known in the Chicago area as a "Tavern Pizza", has a thinner crust than Chicago-style deep dish, and is baked flat rather than in a deep dish pan. The crust is thin and firm enough to have a noticeable crunch, unlike a New York-style pizza, yet thick enough to be soft and doughy on the top. The crust is invariably topped with a liberal quantity of southern-Italian style tomato sauce, which is usually quite herbal or highly spiced, and typically contains no visible chunks of tomato. Next, a layer of toppings is added, and a layer of mozzarella cheese which frequently separates from the bottom crust due to the quantity of tomato sauce. Chicago-style thin crust pizzas are cut into three-to-four-inch (8–10 cm) squares, also known as "party cut", as opposed to a "pie cut" into wedges. Chicago-style thin crust pizza is prevalent throughout the Midwestern US.
Detroit-style pizza is also known as Sicilian Square Pizza. It is a square pizza, with a thick deep-dish crust with toppings placed under the sauce.
Quad City-style pizza is a thin crusted dough that has a “spice mix” that is heavy on malt which lends a toasted, nutty flavor. The sauce contains both red chile flakes and ground cayenne, the smooth, thin tomato spread is more spicy than sweet. The sausage is a thick blanket of lean, fennel-flecked Italian sausage that’s ground twice and spread from edge to edge.