Pizza is a $45.1 billion industry in the United States. Here are the top pizza chains across this great nation, based on gross sales in 2016.

1. PIZZA HUT

Pizza Hut is truly enormous. Raking in more than $5.75 billion in 2016, the chain is best known for its red roof architecture. The style is so distinctive that the blog Used to Be a Pizza Hut collects photos of former Pizza Hut restaurants now turned into other businesses.

2. DOMINO'S PIZZA

With more than $5.47 billion in revenue, Domino's is nipping at Pizza Hut's heels. For decades, Domino's offered a guarantee that your pizza would arrive in 30 minutes or less, or it would be free. The policy was terminated in 1993 in the U.S., and Domino's has since focused on expanding its menu with pasta, sandwiches, and other goodies.

3. LITTLE CAESARS

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Founded in 1959 by Mike and Marian Ilitch, Little Caesars focuses on carry-out pizza at ultra-competitive prices. Using slogans like "Pizza! Pizza!," "Pan! Pan!," and "Deep Deep Dish," the chain offers hot cheese pizzas for just $5.

4. PAPA JOHN'S

Headquartered in Jeffersontown, Kentucky, Papa John's was the first national pizza chain to offer online ordering in the U.S., way back in 2002.

5. PAPA MURPHY'S PIZZA

Papa Murphy's offers exclusively "take and bake" pizza, where the ingredients are put together in front of you, then you bake the pizza at home. It's the only large chain to offer this kind of pizza, and it's a smart business model—stores don't need pizza ovens!

6. CALIFORNIA PIZZA KITCHEN

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The first California Pizza Kitchen launched in 1985 in Beverly Hills, California. The focus is on gourmet pizza, including a line of relatively fancy frozen pizzas. In many locations, CPK also offers gluten-free crust as an option, making it a favorite for gluten-intolerant pizza lovers.

7. MARCO'S PIZZA

Pasquale “Pat” Giammarco founded Marco's Pizza in 1978. The Toledo, Ohio-based chain is now the country's fastest-growing pizza chain, with more than 800 franchised locations across the U.S. as well as in Puerto Rico, the Bahamas, and India. They specialize in what they've dubbed "Ah!thentic Italian."

8. ROUND TABLE PIZZA

In 1958, Bill Larson concluded four years of US Navy service and got a job at a pizza parlor in San Mateo, California. A year later, he founded his own: Round Table Pizza. Using a King Arthur theme, Round Table has often featured knights and shields in its logo. The knight theme originated when Larson saw drawings of King Arthur's court eating pizza.

9. MELLOW MUSHROOM

The brainchild of two Georgia Tech students, Mellow Mushroom opened in Atlanta, Georgia as a one-off pizzeria. Today, it boasts more than 150 locations, and is regularly inching further westward.

10. CICIS

Cicis is the world's largest pizza buffet chain. It features all sorts of wild stuff including a macaroni-and-cheese pizza.

Source: PMQ Pizza Magazine