Sunday is National Pizza Day

(CNN) – Sunday, Feb. 9 is National Pizza Day!

This is a small Domino's pizza made in a Domino's Pizza shop in downtown Pittsburgh on Monday, July 15, 2019. (AP Photo/Gene J. Puskar)

For centuries, pizza was primarily a dish enjoyed in Italy.

In the early 20th century, the first American-style pizza shops popped up in New York and New Jersey, selling what were called “tomato pies.”

But pizza truly became part of American culture after World War II, as U.S. soldiers stationed in Italy developed quite the taste for it.

So, just how popular is pizza?

According to the National Association of Pizza Operators, about 3 billion pizzas are sold in the U.S. each year.

And the American Pizza Community says there are 34 million different ways to order a pie, depending on size, cheese, crust, sauce and toppings.

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