The great emigration from Italy to America ended abruptly with the Immigration act of 1924, 84 years ago. I doubt their are 16 million born in Italy immigrants in the US today. More like a million. The 16 million figure is more likely the number of Americans with Italian ancestry.
The US Census websites states that there are 604,000 foreign born Italian Americans. The rest are US born, about 15 million of those, me included :), you might call us U.S. Italian Americans.