There was no 1921 Census of Ireland, because of the civil war. The majority of the island of Ireland became the Irish Free State and the first census was taken in 1926 on the night of 18/19 April. A statement was made in 2012 by the government that the census would be released to the public early with a target date of 2016 but little progress seems to have been made.
In apparent contradiction, the National Archives of Ireland website still states that it will not be released to the public until January 2027. A minister is quoted as saying that "the confidentiality of all statistical returns from individuals, households and business is guaranteed by law […] I am satisfied, therefore, that the 100 years period […] strikes the right balance". Others argue that early release would boost tourism. Watch this space but don't hold your breath.
Six of the nine counties of the province of Ulster remained part of the United Kingdom, Northern Island, and the first census was also taken on the night of 18/19 April 1926 with the police used as enumerators. The paperwork associated with 1926 Census of Northern Ireland was pulped during WW2, for reasons that are not completely clear.
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