The impact of such numbers in such concentration was profound whether in physical terms - expressed in such problems as water supply, sanitation and housing, in social terms - through the impact on family and the changing structure of society, or in economic terms - through the problems attendant upon new systems of commercial and industrial organisation. The political and administrative problems of creating a new framework of organisation for local government were reflected in the complexities of the changing map of administrative areas. Yet despite the significance of the process of urbanisation it is not easy to analyse the basic elements of population and socio-economic change from census sources alone. Although contemporaries stressed the importance of urban growth in census reports and tabulations, especially from 1841, they did not find the task of defining and analysing urban population an easy one.