Donnés relatives à la population en Amérique du Nord et dans les pays de l'OCDE:
In OECD countries the population tends to concentrate in urban regions. In 2003, almost half of the total OECD population (46%) lived in urban regions. This concentration is mainly due to the benefits of "agglomeration economies" . People want to live where firms – and therefore job opportunities – are concentrated. For their part, firms want to locate where demand – and therefore population – is large. Thus, the presence of firms and workers in an urban region will attract firms and more workers from other regions, thus increasing concentration.
This cycle is likely to continue up to a certain threshold, beyond which "diseconomies of agglomeration" tend to arise. When the concentration of people and firms in the same place is too great, increased pollution, traffic congestion, real estate prices and social tensions generate costs that eventually exceed the initial benefits from agglomeration.
L'occident en chiffres: le vieillissement de la population