The population of the State has exceeded four million for the first time since 1871, according to new estimates from the Central Statistics Office.
The CSO's estimate of the population at April 2004 is 4.04 million, an increase of 1.6% since April 2003.
The population and migration estimates show that 50,000 immigrants in the year to April 2004 contributed to this increase.
A third of the immigrants came from countries outside the EU and the US, and another third were Irish people returning from abroad.
The figures show that 18,500 people left the country, the lowest figure since 1987. The natural increase in the population from births and deaths exceeded the contribution from migration.
Meanwhile, new employment figures, also released by the CSO, show that almost 43,000 new jobs were created in the year to the end of May.
