Pizza arrived in the United States in the early 20th century along with waves of Italian immigrants who settled primarily in the larger cities of the Northeast, such as New York, Philadelphia, Boston and Baltimore. After American soldiers stationed in Italy returned from World War II, pizza and pizzerias rapidly grew in popularity.^[1]

During the latter half of the 20th century, pizza became an iconic food with considerable acceptance in the United States. Numerous regional variations have evolved, with many bearing only a casual resemblance to the Italian original. Pizza is a popular fast food item produced by many small restaurants as well as several large pizza restaurant chains. The United States pizza restaurant industry was worth $37 billion in 2015.^[2][3]

The first pizzeria in the U.S., Lombardi's,^[4] opened in New York City's Little Italy in 1905,^[5] producing a Neapolitan-style pizza. The word "pizza" was borrowed into English in the 1930s; before it became well known, pizza was generally called "tomato pie" by English speakers. Some regional pizza variations still use the name tomato pie.^[6][7]

Distinct regional types developed in the 20th century, including Buffalo,^[8] California, Chicago, Detroit, Greek, New Haven, New York, and St. Louis styles.^[9] These regional variations include deep-dish, stuffed, pockets, turnovers, rolls, and pizza-on-a-stick, each with several combinations of sauce and toppings.

Thirteen percent of the United States population consumes pizza on any given day.^[10] Tens of thousands of pizzerias, food stands, chains such as Domino's, Pizza Hut, and Little Caesars, pies from take and bake shops, and chilled or frozen pizzas from supermarkets make pizza readily available both to diners and at-home consumers nationwide.

Common toppings for pizza in the United States include pepperoni, sausage, salami, ground beef, ham, bacon, olives, mushrooms, onions, peppers, anchovies, chicken, tomatoes, spinach, and pineapple.

American pizza (particularly thin-crust) is made with a very high-gluten flour (often 13–14% protein content) of the type also used to make bagels; this allows the dough to be stretched thinly and thrown vigorously without tearing. Unlike Italian pizza,^[12] American pizza often has vegetable oil or shortening mixed into the dough. This can range from a small amount in relatively lean doughs, such as New York–style, to a very large amount in some recipes for Chicago-style deep-dish dough.^{[citation needed]}

While tomato sauce is virtually ubiquitous, variations such as white pizza omit it while others replace it with garlic and olive oil or sauces made from other vegetables such as pesto.

The most common cheese used on US pizzas is mozzarella. Other popular cheeses include:^[13]

• Parmesan: a hard aged cheese, available in a variety of moistures. U.S. pizzerias generally use generic parmesan, not PDO Parmigiano Reggiano. Parmesan is often pre-processed and sold in dehydrated, granular form. It generally has a sharp, pungent flavor.
• Provolone: second most popular cheese after mozzarella. Some U.S. pizzerias mix it with low-moisture mozzarella, while a handful use only provolone.
• Romano (generic): a hard, aged cheese. The Italian pecorino romano is made from sheep milk; the commonly used U.S.-made imitations are made from cows' milk, with an enzyme added to simulate the sharper flavors of the original.
• Ricotta: ricotta is used on white pizzas, often covered with another cheese that melts better during baking and holds the ricotta in place.

• Altoona-style pizza is a distinct type of pizza created in the city of Altoona, Pennsylvania, by the Altoona Hotel. The definitive characteristics of Altoona-style pizza are a Sicilian-style pizza dough, tomato sauce, sliced green bell pepper, salami, topped with American cheese, and pizzas cut into squares instead of wedges.^[14]
• California-style pizza is distinguished by the use of non-traditional ingredients, especially varieties of fresh produce. Some typical California-style toppings include Thai-inspired chicken pizza with peanut sauce, bean sprouts, and shaved carrots, taco pizzas, and pizzas with chicken and barbecue sauce as toppings.^{[citation needed]}

• Chicago-style pizza is distinguished by a thick moist crust formed up the sides of a deep-dish pan and sauce as the last ingredient, added atop the cheese and toppings. Stuffed versions have two layers of crust with the sauce on top.^[15][16][17]
• Colorado-style pizza is distinguished by a thick braided, whole-wheat crust topped with a sweet tomato sauce and heavy toppings. It is traditionally served by the pound with a side of honey.^[18][19]
• Columbus-style pizza has a circular shape, pieces cut into short or long rectangles, thin but crispy or bubbly crust, dense toppings that cover the surface, and, usually, provolone cheese and a slightly sweet sauce.^[20][21]
• Dayton-style pizza has a thin, crisp, salty crust dusted on the bottom with cornmeal and topped with a thin layer of thick unsweetened sauce. Cheese and other topping ingredients are heavily distributed and spread edge-to-edge with no outer rim of crust, and the finished pizza is cut into bite-size squares.^{[22][23][24][25]}

• Detroit-style pizza is a rectangular pan pizza with a thick crust that is crispy and chewy. It is traditionally topped with Wisconsin brick cheese that goes all the way to the edges and caramelizes against the high-sided heavyweight rectangular pan. This style of pizza was originally baked in rectangular steel trays designed for use as automotive drip pans or to hold small industrial parts in factories.^[26]
• Grandma pizza is a thin, square pizza, typically with cheese and tomatoes. It is reminiscent of pizzas baked at home by Italian housewives without a pizza oven, and was popularized on Long Island.^[27]
• 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 thick, chewy 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. A significantly different variation in other parts of the country includes using feta cheese, Kalamata olives, and Greek herbs such as oregano.^[26]
• Maryland-style pizza is a rectangular pie with biscuity crust, sweet tomato sauce, smoked provolone.^[28][29]
• Minneapolis-style pizza or Minnesota-style pizza^[30] is a circular thin-crust pizza, cut into squares, with spicy sauce, and hearty toppings. It is popular in the Twin Cities metropolitan area.^[31]
• New Haven–style pizza has a thin crust that varies between chewy and tender (depending on where it is made), baked in coal-fired brick ovens^[32] till charred, offset by the sweetness of tomatoes and other toppings. Also known as "apizza" (pronounced as "ah-beetz" in the local dialect), it has tomato sauce and only grated Romano cheese; mozzarella is considered a topping.^[33]

• New York–style pizza is a Neapolitan-style thin-crust pizza developed in New York City by immigrants from Naples, Italy, where pizza was created.^[34] It is traditionally hand-tossed, moderately topped with southern Italian-style marinara sauce, and liberally covered with mozzarella cheese. It is often sold in generously sized, thin, and flexible slices, typically folded in half to eat. This style of pizza tends to dominate the Northeastern states and is particularly popular in New York, New Jersey, and Connecticut. Jumbo slices of a similar pie are particularly popular in Washington, D.C.^{[citation needed]}
• Ohio Valley–style pizza is pizza that was developed in Steubenville, Ohio, and has made its way up the Ohio River to Pittsburgh, Pennsylvania. It uses a square pizza dough that rises thick but maintains a light consistency. The crust and bottom are crunchy. The sauce on this style of pizza is typically sweet and the pizza is baked without toppings. Immediately after being removed from the oven cold toppings are put on the hot pizza, including the cheese, in prodigious amounts. Most of the cheese melts, but not all. The other toppings used remain cold on top of the cheese.^[35][26]
• Pan pizza is a deep-dish styles like Chicago and Detroit are pan pizzas. A variation of moderate thickness was popularized by Pizza Hut.^{[citation needed]}

• Quad City–style pizza is a pizza style developed in the Quad Cities metro area on the Illinois–Iowa border. It features a thin dough that incorporates seasoning that is heavy on malt, lending a toasted, nutty flavor. The smooth, thin sauce contains both red chili flakes and ground cayenne, and is more spicy than sweet. It is topped heavily with lean, fennel-flecked Italian sausage that is ground twice and spread in crumbles from edge to edge.^[26]
• Sheet pizza is any thin-crust style baked on a baking sheet. It is typically rectangular (like the sheet) and served for events with a large number of people.^{[citation needed]}
• Sicilian pizza in the United States is typically a square pie with a thick crust.^[36][37] It is derived from sfinciuni, a thick-crust variety from Sicily, and was introduced in the US by early Sicilian immigrants. Sicilian-style pizza is popular in Italian-American enclaves in the Northeast, Metro Detroit, and Portland, Oregon.^[37]
• South Shore Bar pizza is distinguished by a thin crust, almost cracker-like, and is baked, or at least partly baked, in a shallow pan for an oily crust. Cheese covers the entire pizza, including the crust, leaving a crispy edge where the cheese meets the pan or oven surface. Bar pizzas are usually served in a bar or pub and are usually small in size (around 10" in diameter). This style of pizza is popular in the Boston area, particularly the South Shore.^[38]
• St. Louis–style pizza is a variant of thin-crust pizza popular around St. Louis and southern Illinois notable for its use of distinctive Provel cheese instead of (or, rarely, in addition to) mozzarella. Its crust is thin enough to become very crunchy in the oven, sometimes being compared to a cracker, and toppings are usually sliced instead of diced. Even though round, St. Louis-style pies are always cut into small squares.^[26]
• Italian tomato pie is a square-cut thick-crust pizza topped with chunky tomato sauce and sprinkled with pecorino romano cheese, very similar to Sicilian sfinciuni. Also known as party pizza, pizza strips, gravy pie, church pie, red bread, strip pizza, and bakery pizza. Popular in several areas around the Northeast, especially Rhode Island, Philadelphia and Utica, New York.^{[citation needed]}
• Trenton tomato pie^[39] or New Jersey tomato pie^[40] is a circular thin-crust pizza where the cheese and toppings are placed before the sauce. Named after Trenton, New Jersey.^[41]

• Italian-American cuisine
• Mexican Pizza – created by the U.S.-based chain Taco Bell
• List of pizza varieties by country