Irish Americans are citizens of the United States who can trace their ancestry to Ireland. A total of 36,278,332 Americans—estimated at 11.9% of the total population—reported Irish ancestry in the 2008 American Community Survey conducted by the U.S. Census Bureau.[2] Roughly another 3.5 million (or about another 1.2% of Americans) identified more specifically with Scotch-Irish ancestry.
According to the Dictionary of American History, approximately "50,000 to 100,000 Irishmen, over 75 percent of them Catholic, came to America in the 1600s, while 100,000 more Irish Catholics arrived in the 1700s." Indentured servitude was an especially common way of affording migration, and in the 1740s the Irish made up nine out of ten indentured servants in some colonial regions.
Effects of the great Irish famine:
One of the most obvious effects of the famine was emigration. Although the famine itself probably resulted in about 1 million deaths, the resultant emigration caused the population to drop by a further 3 million. About 1 million of these are estimated to have emigrated in the immediate famine period, with the depression that followed continuing the decline until the second half of the 20th century. These migrants largely ended up in North America, with some in Australia and in Britain.
Between 1845 and 1855, 1.5 million people left for good. In 1845, emigration was at the pre-famine rate of 50,000 per year. In 1846 100,000 left. It peaked in 1847, when 250,000 left. Over the next 5 years it averaged 200,000 per year, before the numbers fell off. By 1855, the rate was down to 70,000 per year .