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>. Output and number of collieries, North Wales and South Wales, 1854-1874 Output. Numbers employed and output per head, by region and county, 1874-1945 Output. Numbers employed and productivity, North Wales and South Wales, 1945-1974 Output of anthracite, South Wales and UK, 1854-1974 Output from government open-cast workings, South Wales, 1943-1972 Output and numbers employed, South Wales, as a percentage of UK, 1874-1974 Shipments (coastal and foreign) from South Wales ports, 1816-1974 Shipments. Exports of coal, coke and patent fuel from South Wales ports, 1854-1937 Shipments. Foreign and coastal shipments from each port (Cardiff, Swansea, Newport, Llanelli, Milford, Neath, Porthcawl), 1780-1974 Colliery deaths, number and rate, underground and total, South Wales, 1853-1974; and North Wales (number only), 1853 -1938 Mechanisation. Number, type and work done by mechanical coal cutters; number of coal conveyers; and amount of electricity used in mines, North Wales and South Wales, 1900-1945 Mechanisation. Percentage of coal output cut and conveyed by machinery (1937-1960); and percentage power-loaded (194 7-1975), South Wales, 1937-1975 Prices. Average pit head prices, North Wales and South Wales, 1878-1938; and f.o.b. prices for steam coal (large and small), South Wales, 1840-1934 Costs and proceeds. Average wage coal, total cost and proceeds, per ton, North Wales and South Wales, 1917-1974 The number and annual output of members of the Coal Owners' Association, 1863-1946 Output from Aberdare parish, 1844-1874; and coal carried by the Taff Vale Railway, 1841-1921 Output of coke and number of coke ovens, South Wales, 1905-1974 Please note: this study does not include information on named individuals and would therefore not be useful for personal family history research.