By CBS3 Staff

PHILADELPHIA (CBS) — Calling all pizza lovers, Sunday is the perfect day to grab a pie at your favorite shop — it’s National Pizza Day. National Pizza Day is celebrated on Feb. 9.

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

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

According to the National Association of Pizza Operators, about three billion pizzas are sold in the United States each year.