This machine-readable version of John Williams' <i>Digest of Welsh Historical Statistics</i> is the result of a collaboration between the Statistical Directorate of the National Assembly for Wales, the History Data Service and the Centre for Data Digitisation and Analysis at Queen's University Belfast. John Williams' <i>Digest of Welsh Historical Statistics</i> is intended to provide a service for those working on the history of modern Wales. It arises from a belief that the quantitative element is a necessary and important part of the historical record; from an awareness that it was an aspect that was particularly inaccessible for scholars of Welsh history; and from a conviction that some encouragement in the use of quantitative material was necessary. It is modelled on the two volumes dedicated to British historical statistics: Mitchell, B.R. and Deane, P. (1962) <i>Abstract of British historical statistics</i> and Mitchell, B.R. and Jones, H.G. (1971) <i>Second abstract of British historical statistics</i>. Total population and intercensal change by sex by county, 1801-1971 Number of females per 1000 males by county, 1801-1971 Age and marital condition by sex, 1841-1971 Area/acreage by county, 1841-1971 Population of Registration Counties as constituted at the time of each Census, 1841-1911 Comparative area and population of Registration, Ancient and Administrative Counties, 1891 Parish Register returns of baptisms, burials and marriages, 1700-1840 Estimated mid-year population by sex, 1841-1974 Estimated mid-year population totals by county, 1903-1974 Number of deaths by sex, crude death-rates and infant mortality, 1838-1974 Number of births and birth-rates, 1839-1974 Number of marriages and rate per 1000 population, 1839-1974 Population of towns, 1801-1971 Net migration and natural increase, number and per cent for each, inter-censal period, by county, 1841-1971 Number born in Wales and living in United States, 1850-1970 Number of Welsh speakers by sex, by county and county borough, 1891-1971 Welsh speakers as a percentage of total population over three years of age, by county and county borough, 1891-1971 Welsh-speaking population by age, 1901-1971 Please note: this study does not include information on named individuals and would therefore not be useful for personal family history research.