That may be a more interesting question than you think:
historynewsnetwork.org/…/how-italians-became-whit…. This is, of course, all irrelevant pseudoscience.

How Italians Became ‘White’
Italians who had come to the country as “free white persons” were often marked as black because they accepted “black” jobs in the Louisiana sugar fields or because they chose to live among African-Americans.
HNN