Catholic Church in Ireland
In the 2016 Irish census 78.3% of the population identified as Catholic in Ireland; numbering approximately 3.7 million people. Unlike Catholics in the United States, Ireland has seen a significant decline from the 84.2% who identified as Catholic in the 2011 census.
Irish Americans
Of the approximately 250,000 immigrants from Ireland to the United States between 1717 and 1775, approximately 10,000 were Catholics (or about 4 percent). By 1800, the number of Irish Catholics who had immigrated had increased in absolute terms to approximately 20,000, but had declined in proportional terms (to less than 3 percent), as one-sixth of the white population in the United States by that time (which in the 1800 U.S. Census was 4,308,083) was composed of those of Scotch-Irish descent (or approximately 718,000). Like most Catholics in the United States at the time, these Irish Catholics settled largely in Maryland and Pennsylvania. In 1700, the estimated population of Maryland was 29,600, about one-tenth of which was Catholic (or approximately 3,000). By 1756, the number of Catholics in Maryland had increased to approximately 7,000, which increased further to 20,000 by 1765. In Pennsylvania, there were approximately 3,000 Catholics in 1756 and 6,000 by 1765. By the end of the American Revolutionary War in 1783, there were approximately 24,000 to 25,000 Catholics in the United States out of a total population of approximately 3 million. However, most of the Catholic population in the United States during the colonial period came from England, Germany, and France, not Ireland.