Irish Americans are an ethnic group comprising Americans who have full or partial ancestry from Ireland, especially those who identify with that ancestry, along with their cultural characteristics. About 33.3 million Americans—10.5% of the total population—reported Irish ancestry in the 2013 American Community Survey conducted by the U.S. Census Bureau. This compares with a population of 6.4 million on the island of Ireland. Three million people separately identified as Scotch-Irish, whose ancestors were Ulster Scots who emigrated from Ireland to the United States.