Analysis of information sources in references of the Wikipedia article "آمریکاییهای ایرلندیتبار" in Persian language version.
The term [Scotch-Irish] had been in use during the eighteenth century to designate Ulster Presbyterians who had emigrated to the United States. From the mid-1700s through the early 1800s, however, the term Irish was more widely used to identify both Catholic and Protestant Irish... as political and religious conflict between Catholics and Protestants both in Ireland and the United States became more frequent, and as Catholic emigrants began to outnumber Protestants, the term Irish became synonymous with Irish Catholics. As a result, Scotch-Irish became the customary term to describe Protestants of Irish descent... The famine migration of the 1840s and '50s that sent waves of poor Irish Catholics to the United States together with the rise in anti-Catholicism intensified this attitude. In no way did Irish Protestants want to be identified with these ragged newcomers.
...there is a tendency in many academic and literary quarters to lump the Scots-Irish in with the Irish themselves. More than 40 million Americans claim Irish descent, exclusive of those Scots-Irish who have self-identified themselves on census reports under other categories such as Scottish or 'native American.' Interestingly, more than half of these are of Scots-Irish ancestry.
Between 250,000 to 400,000 Scots-Irish migrated to America in the eighteenth century...
During the 1970s and 1980s, when studies of "white ethnics" were very much in vogue, several different national surveys quite in- dependently turned up a surprising finding: most Americans who thought of themselves as "Irish" were Protestant, not Catholic. Donald Akenson's review of these surveys, for example, suggests that anywhere from 51 to 59 percent of respondents (depending on the survey) who identified themselves as Irish were Protestant, with about a third being Catholic and the rest being non-Christian or professing no religion. This pattern has not changed. Table 1 presents data from successive installments of the General Social Survey (GSS) conducted over the period 1990–2000. Of the 1,495 respondents who identified themselves as "Irish," 51 percent were Protestant and 36 percent were Catholic (see last column in Table 1).