While the Great Famine gave emigration a major boost, it was already well-established before 1845, with some estimates of 1.5 million Irish people crossing the Atlantic in the period from 1815-45 alone. Economic motives have been the key factor over the last two centuries.
Lack of job opportunities, especially for those who did not have the right connections, or poor pay and conditions in Ireland, pushed many into leaving for the prospect of higher wages and secure employment in England. [...]
England's wartime economy (1939-45) and post-war boom attracted many Irish people to expanding towns such as Luton.
Other emigrants, Catholic and Protestant, Nationalist and Unionist, might leave Ireland because of political unrest. [...]
Others left either because they found Ireland's social and cultural life too restricting; to escape family friction; or to get an abortion. Divorce and contraception were illegal and job prospects were limited.
Read this text from the UK National Archives Moving Here project. Which push and pull factors can you identify?