I believe Pizza/Pita like flat-bread type foods have existed in the Mediterranean since ancient Greek times. https://en.wikipedia.org/wiki/History_of_pizza htt

I believe Pizza/Pita like flat-bread type foods have existed in the Mediterranean since ancient Greek times. https://en.wikipedia.org/wiki/History_of_pizza https://en.wikipedia.org/wiki/History_of_pizza if one is to trust the historical information quoted on wikipedia, pizza was popular in Italy (Naples in particular) already in the 19th century, well before immigrants made it popular in the US. So I think "Pizza effect" is a bit of a misnomer