Italian influence on American history can be traced back to Christopher Columbus and Americo Vespucci. The Founding Fathers, especially Jefferson and Franklin, were familiar with the Italian language and culture and with Roman history. Jefferson was a supporter of Filippo Mazzei and encouraged him in the early 1770s to bring Italian vintners to Virginia.
Though not successful in that venture, Mazzei became actively involved in the colonists' struggle with England. Writing in the Virginia newspapers as "Furioso," he was one of the first to urge Americans to declare independence and form a unified constitution to govern all thirteen colonies. Some of his phraseology later found its way into Jefferson's Declaration of Independence.
Source: http://blogs.lib.luc.edu