<Tr> <Th_colspan="2"> Related ethnic groups </Th> </Tr> <Tr> <Td_colspan="2"> Ulster Scots, Scottish Americans, English Americans, Irish Americans, Americans </Td> </Tr> <P> Scotch - Irish (or Scots - Irish) Americans are American descendants of Presbyterian and other Ulster Protestant Dissenters from various parts of Ireland, but usually from the province of Ulster, who migrated during the 18th and 19th centuries . 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 . The term Scotch - Irish is used primarily in the United States, with people in Great Britain or Ireland who are of a similar ancestry identifying as Ulster Scots people . Most of these emigres from Ireland had been recent settlers, or the descendants of settlers, from the Kingdom of England or the Kingdom of Scotland who had gone to the Kingdom of Ireland to seek economic opportunities and freedom from the control of the episcopal Church of England and the Scottish Episcopal Church . These included 200,000 Scottish Presbyterians who settled in Ireland between 1608 - 1697 . Many English - born settlers of this period were also Presbyterians, although the denomination is today most strongly identified with Scotland . When King Charles I attempted to force these Presbyterians into the Church of England in the 1630s, many chose to re-emigrate to North America where religious liberty was greater . Later attempts to force the Church of England's control over dissident Protestants in Ireland were to lead to further waves of emigration to the trans - Atlantic colonies . </P> <P> The term is first known to have been used to refer to a people living in Northeastern Ireland . In a letter of April 14, 1573, in reference to Ulster, Elizabeth I of England wrote: "We are given to understand that a nobleman named' Sorley Boy' (MacDonnel) and others, who be of the Scotch - Irish race ..." This term continued in usage for over a century before the earliest known American reference appeared in a Maryland affidavit in 1689 / 90 . </P>

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