History of Irish census records

Censuses of population are taken by governments to establish numbers and characteristics of a country's inhabitants. The first full government census of Ireland was taken in 1821 with further censuses at ten-yearly intervals from 1831 through to 1911. No census was taken in 1921, because of the War of Independence. The first census of the population of the Irish Free State was taken in 1926. The censuses from 1851 to 1911 were taken under the supervision of the Registrar General of Births, Deaths and Marriages. The 1926 and all subsequent censuses were taken under the Statistics Act, 1926. The responsibility for taking censuses was transferred from the Registrar General to the newly established Statistics Branch of the Department of Industry and Commerce. The Statistics Branch has since become the Central Statistics Office.

To date censuses have been taken in 1926, 1936, 1946, 1951, 1956, 1961, 1966, 1971, 1979 (the census due in 1976 was cancelled as an economy measure), 1981, 1986, 1991, 1996, 2002 and 2006. The returns for 1926 - 1946 and part of those for 1951 are held in the National Archives, but they remain under the control of the Central Statistics Office, to the extent that the staff of the National Archives are not permitted to examine them for any purpose. The more recent returns are still held by the Central Statistics Office. The 1926 Census Returns will be released to public inspection in January 2027.

The original census returns for 1861 and 1871 were destroyed shortly after the censuses were taken. Those for 1881 and 1891 were pulped during the First World War, probably because of the paper shortage. The returns for 1821, 1831, 1841 and 1851 were, apart from a few survivals, notably for a few counties for 1821 and 1831, destroyed in 1922 in the fire at the Public Record Office at the beginning of the Civil War.

The population of the island of Ireland in 2012 was approximately 6.4 million comprising 4.58 million in the Republic of Ireland with another 1.8 million in Northern Ireland. Although this is a significant growth over recent years, it is lower than historical figures.

In 1841 the population of the 26 counties which would later form the Republic of Ireland was over 6.5 million people. The Great Famine and the emigration it caused had a dramatic effect, so that by 1871 the 26-county population had dropped by over a third to four million, and by 1926 had reduced further to three million. It held firm around three million until the early 1970s when the population began to rise again. Future predictions are for the population to continue to rise until 2031 when it is predicted to be just over five million. The Republic of Ireland is one of the few remaining developed economies to have growth of this scale.

Below are some statistics to illustrate the rise, fall and rise again of the population since 1841. The statistics also illustrate a massive population shift from the west to the east of the country and increasing urbanisation. Counties such as Mayo, Roscommon, Donegal and Leitrim have become depopulated while counties surrounding Dublin including Wicklow, Kildare, Louth and Meath have seen rapid population growth in recent years.