This polygon shapefile contains the output area (OA) boundaries and population statistics for England and Wales. Output areas (OAs) are created for Census data, specifically for the output of census estimates. The generalised set of OA boundaries has been created automatically with manual intervention only where necessary to correct any features that had become too distorted and are more suitable for such applications as thematic mapping. The boundaries have been generalised to a tolerance of 20 metres, with intermediate points being removed within this tolerance if they did not significantly change the angle of the line. The OA is the lowest geographical level at which census estimates are provided. There are 175,434 output areas in England and Wales. They were created around a target of 125 resident households, and 37.5% lie between 120 and 129 households, whilst 79.5% lie between 110 and 139 households. Some 5% lie between 40 households - the confidentiality threshold - and 99 households, and many of these are a single parish (or community in Wales). The output areas nest within ward and parish (community in Wales) boundaries legally in place at the end of 2002. Draft boundaries were used in a few local authorities where final versions did not become available. Information on the operative dates for the district, ward and parish boundaries in each local authority is listed Here (as an Excel file), together with the number of Output Areas in each authority.This dataset is intended for researchers, students, and policy makers for reference and mapping purposes, and may be used for basic applications such as viewing, querying, and map output production, or to provide a basemap to support graphical overlays and analysis with other spatial data.