Sources:  PMQ Pizza Magazine Pizza Power Report 2010.

List Notes: 

1. As of March 2009, there were approximately 64,951 pizza restaurants in the United States, 42% were chains and 58% were independent restaurants. Consumers report that 45 percent of pizza orders are takeout, 36 percent are delivery and 20 percent are dine-in. Pizza sales for the year 2009 were $32.286 billion dollars with independent restaurants accounting for 51.66% of total pizza sales in the United States. Approximately 3 billion pizzas are sold in the U.S. each year. Pizzerias represent 17% of all restaurants and pizza accounts for more that 10% of all foodservice sales. Americans eat approximately 100 acres of pizza each day, or about 350 slices per second. 16% of the pizzas ordered in the United States in 2009 were ordered online.
2. Cheese accounts for roughly 40% of the cost of a restaurant pizza, making it the most important menu ingredient by far with respect to costs. 86% of pizza consumers say they prefer to choose their own toppings as opposed to ordering a specialty pizza.
3. Pepperoni is by far America's favourite topping, (36% of all pizza orders). Approximately 251,770,000 pounds of pepperoni are consumed on pizzas annually. Other popular pizza toppings are mushrooms, extra cheese, sausage, green pepper and onions. 62% of Americans prefer meat toppings on their pizza, while 38% prefer vegetarian toppings.
4. Delivery accounts for 34% of all pizza meal occasions compared to just 2% of all other restaurant meals.
5. There is one pizza restaurant for every 4,330 U.S. residents. The Big Four pizza chains (Pizza Hut, Domino's Pizza, Papa John's and Little Caesars Pizza) represent 36.8% of industry sales at $10.81 billion. The top 50 pizza chains in the United States own 42% of pizzerias and control 48.34% of pizza sales.

Top 5 facts sources: PMQ Pizza Magazine "Pizza Power Report 2010"., Food Industry News, Blumenfeld and Associates.