Records Ireland - Census
A census of the Irish population was taken every ten years from 1821 until 1911 and manuscript returns for each household survive for all 32 counties for 1901 and 1911.
The National Archives of Ireland are digitising the 1901 and 1911 census records. The records for 1911 are being digitised first, then those for 1901. All thirty-two counties for 1911 are now online. Fully indexed by name and with free access to the digitised images of the original manuscript household forms, the returns can be viewed on the census site at http://www.census.nationalarchives.ie
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.
Prior to the destruction of the 1851 census, Dr. D.A. Chart of the Public Record Office compiled a comprehensive list of the names and addresses of heads of households for Dublin City and this survived. MADDENs from the 1851 Dublin census have been extracted.
Some fragments for earlier census survive.
The 1901 census for Clare is available as a free online surname search from the Clare County Library site. On the same site, there is also the 1659 Census of Clare and the 1866 Census of Kilfenora and Kiltoraght Parishes.
The 1901 census for Leitrim, Roscommon, Mayo & Sligo can be searched at the Leitrim-Roscommon Genealogy Website.