ABSTRACT
The distribution of population over a territory always leads to aggregates of various sizes: households, hamlets, villages, towns and cities. There is in the long-run a trend towards an increase in the size and the concentration of the population in the aggregates. This evolution has not always been continuous in the past. However, the process of concentration of the population has been almost continuous and of an unprecedented intensity since at least two centuries in many developed countries: more than 80 per cent of the total population is now concentrated in the largest towns and cities, against about 20 per cent before Ad 1800.
