The Irish diaspora (Irish: Diaspóra na nGael) refers to Irish people and their descendants who live outside Ireland.
The phenomenon of migration from Ireland is recorded since early Medieval times, but it is only possible to quantify it from around 1700: since then between 9 and 10 million people born in Ireland have emigrated. This is more than the population of Ireland at its historical peak in the 1840s of 8.5 million. The poorest of them went to Great Britain, especially Liverpool; those who could afford it went further, including almost 5 million to the United States.
After 1840, emigration from Ireland became a massive, relentless, and efficiently managed national enterprise. In 1890 40% of Irish-born people were living abroad. By the 21st century, an estimated 80 million people worldwide claimed some Irish descent, which includes more than 36 million Americans who claim Irish as their primary ethnicity.
As recently as the second half of the nineteenth century, the majority of Irish emigrants spoke Irish as their first language. This had social and cultural consequences for the cultivation of the language abroad, including innovations in journalism. The language continues to be cultivated abroad by a small minority as a literary and social medium.
Joe McHugh is the Republic of Ireland's Minister of State for the Diaspora.
The term Irish diaspora is open to many interpretations. The diaspora, broadly interpreted, contains all those known to have Irish ancestors, i.e., over 100 million people, which is more than fifteen times the population of the island of Ireland, which was about 6.4 million in 2011. It has been argued the idea of an Irish diaspora, as distinct from the old identification of Irishness with Ireland itself, was influenced by the perceived advent of global mobility and modernity. Irishness could now be identified with dispersed individuals and groups of Irish descent. But many of those individuals were the product of complex ethnic intermarriage in America and elsewhere, complicating the idea of a single line of descent. "Irishness" might then rely primarily on individual identification with an Irish diaspora.
The Government of Ireland defines the Irish diaspora as all persons of Irish nationality who habitually reside outside of the island of Ireland. This includes Irish citizens who have emigrated abroad and their children, who are Irish citizens by descent under Irish law. It also includes their grandchildren in cases where they were registered as Irish citizens in the Foreign Births Register held in every Irish diplomatic mission. (Great-grandchildren and even more distant descendants of Irish immigrants may also register as Irish citizens, but only if the parent through whom they claim descent was registered as a citizen before the descendant in question was born.) Under this legal definition, the Irish diaspora is considerably smaller—some 3 million persons, of whom 1.2 million are Irish-born emigrants. This is still a large ratio for any country.