This chapter describes major collaborations between the Great Britain Historical geographic information systems (GIS) and medical researchers, funded by the UK's Economic and Social Research Council under their 'Health Variations' and 'New Dynamics of Aging' programmes. It discusses alternative approaches taken to creating time series for consistent geographical areas. The chapter describes how individual-level information from the Office of National Statistics Longitudinal Study and the National Survey of Health and Development, generally known as the 1946 Birth Cohort, were linked to area data and a GIS framework. It describes the evolution of the quite different geography of local government districts created in 1894. The chapter discusses the statistical reporting geography of England and Wales,?1911–1973. What follows relates specifically to England and Wales: the other components of the United Kingdom, Scotland and Ireland, have always had quite separate systems of local administration and demographic reporting, but until 2007 Wales was fully integrated into England.