As of 2008, over 36 million Americans claimed Irish Ancestry.

According to a Wikipedia article,a total of 36,278,332 Americans—estimated at 11.9% of the total population—reported Irish ancestry in the 2008 American Community Survey conducted by the U.S. Census Bureau.

The only self-reported ancestral group larger than Irish Americans is German Americans.[2] In addition roughly another 3.5 million (or about another 1.2% of Americans) identified more specifically with Scots-Irish ancestry.

Eight Irish Americans signed the United States Declaration of Independence, and 22 American Presidents, from Andrew Jackson to Barack Obama, have been at least partly of Irish ancestry.