Given the motley lineage of most Americans whose families have been here at least a couple of generations, I don't think pigeonholing people by their last names is helpful. You can be a Smith or a McDonald and still be entitled to call yourself Italian-American because of maternal descent.
There are plenty of Americans who can claim Italian ancestry who wouldn't be considered "Italian American" by the public because they don't fit the stereotype of what that requires (being from a Northeastern state, having a last name that ends in a vowel, having olive skin and dark hair).
My last name is one of those boring waspy names but I'm also Italian, German, Swiss and Irish on my mom's side. You can't trust a last name. Al Smith was half Italian and his last name was Smith. Same story with Christie.
