NEW YORK (CBSNewYork) – On Ellis Island, they’re celebrating the history of pizza, and the immigrant families who brought this delicious food to America.

From cheese to pepperoni, thin crust to deep dish, CBS2’s Cindy Hsu has more on the secret stories behind some of your favorite slices.

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Visitors to Ellis Island were treated to free pizza Wednesday to kick off a new exhibit there about some of the immigrant families who brought it to America.

Joseph Riggio’s grandfather immigrated from Italy in 1904. He showed Hsu a picture of his mother Maria Riggio, who along with her husband opened New York Pizza Suprema in 1964. The restaurant is still going strong, right across from Penn Station and Madison Square Garden.

Roberto Caporuscio also immigrated from Italy and opened Keste Pizza & Vino on Bleecker Street. He says pizza delivery started in Naples in the 1600s. The delivery container was heated with hot coals on the bottom to keep the pizza warm.

John Carlo Mandara is 11 and says his grandfather immigrated from a very tough life in Positano, Italy.

“My grandfather, he would have to carry 50 pounds of coal over mountains so his village could use it,” he said.

“To come over not knowing what was on this side, not speaking any English, and just to work hard and and work hard,” said John Mandara of Posa Posa pizza.

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While the families loved sharing their history, some secrets they won’t tell.

Hsu tried to get the secret from Ricky and Joe Piscopo, who own Johnny’s in Mount Vernon.

“And what’s the secret to your pizza?” Hsu asked.

“Hard work,” said Joe.

“Long hours,” said Ricky.

The free pizza is only on Ellis Island for Wednesday’s kick off, but the exhibit will be there through October.

For more information about Ellis Island and to plan your trip, click here.

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Experts say 13 percent of the U.S. population eats pizza on any given day.