Pizza is among the most popular foods in America. Americans were eating 350 slices per second by the end of the twentieth century, making pizza a $32 billion industry. Children aged three to eleven ranked pizza their favorite lunch or dinner meal in 2000.

Pizza consists of flat dough baked with toppings of tomato sauce, cheese, and a varying assortment of vegetables and meats. Pizza has been made in the United States since the early 1900s, when Italian immigrants first came to America. Italian immigrant Gennaro (or, Giovanni, depending on the source) Lombardi opened the first pizzeria in 1905 in the portion of New York City called Little Italy.

Although pizzerias had spread across the country by the 1930s, American soldiers returning from Naples, Italy, at the end of World War II (1939–45) made pizza a true national fad. The soldiers craved the food they had savored in Italy. Pizzerias sprang up across...