High Quality Content by WIKIPEDIA articles! Scotch-Irish (or Scots-Irish) Americans are an estimated 250,000 Presbyterian and other Protestant dissenters from the Irish province of Ulster who immigrated to North America primarily during the colonial era and their descendants. Some scholars also include the 150,000 Ulster Protestants who immigrated to America during the early 19th century, and their descendants. Most of the Scotch Irish were descended from Scottish and English families who colonized Ireland during the Plantation of Ulster in the 17th century. While an estimated 36 million Americans (12% of the total population) reported Irish ancestry in 2006, and 6 million (2% of the population) reported Scottish ancestry, an additional 5.4 million (1.8% of the population) identified more specifically with Scotch Irish ancestry. People in Great Britain or Ireland that are of a similar ancestry usually refer to themselves as Ulster Scots, with the term Scotch-Irish used only in North America.