Why take censuses in Ireland?
Ireland became part of the United Kingdom after the Act of Union in 1800. Before then, public administration in Ireland was quite unsystematic. After 1800, London found itself in charge of a place about which it realised it knew very little. The early decades of the nineteenth century therefore saw a sustained effort to measure and record Ireland in a way that had never happened before.
The first true census in the new United Kingdom was taken in Ireland in 1821. Earlier headcounts had taken place in England and Wales, but this was the first census that we would recognise as modern, listing names and family relationships, occupations and addresses. It was certainly flawed - the enumerators were paid by the number of returns they produced, a serious incentive to invent - but it was complete for the entire island.
Censuses were then held every ten years, becoming more detailed and comprehensive as Victorian public administration grew in competence and reached into every corner of Ireland.
What happened to the Irish census returns?
By 1914, ten full censuses had been carried out in Ireland. The returns from 1861 and 1871 were destroyed shortly after they were taken, but there were still no fewer than eight full sets of returns in existence, the earliest four transferred to the Public Record Office, the others still held by the Office of the Registrar-General, the body responsible for census-taking after 1851.
Then things started to go wrong. First, at some point during the first World War, the Registrar-General ordered the 1881 and 1891 returns to be pulped, for reasons that are still unclear.
And then in June 1922, in the bombardment that began the Civil War, the Public Record Office in Dublin was destroyed and every single item held in its Strong Room, including almost all of the four earliest censuses, was obliterated without trace.
The only two censuses to survive in their entirety were from 1901 and 1911. Scraps from the earlier censuses that were not in the Strong Room - out for rebinding, in use in the Reading Room, not yet returned to their shelves - were also spared.
All of the surviving pre-1922 returns are now imaged and freely searchable at the National Archives of Ireland website, census.nationalarchives.ie