Basing Policies on Facts, not Biases
Policymakers have understandably been much concerned with the speed and magnitude of urban growth. Many would prefer slower growth or none at all; slower growth would theoretically give them more flexibility to deal with urban problems. Generally, they attempt to slow growth by restricting incoming migration but, as Chapter 3 argues, this rarely works.
Moreover, such efforts reflect a poor understanding of the demographic roots of urban growth. Most people think that migration is the dominant factor; in fact, the main cause today is generally natural increase. Reclassification of formerly “rural” areas and residents as “urban” also contributes to urban growth.
In developing countries, city growth during the “second wave” (see Box 2) is being driven by higher rates of natural increase than in Europe and North America at the height of their urbanization processes.
The latest comprehensive research effort to separate natural increase from other components of urban growth puts the contribution of natural increase at about 60 per cent in the median country.(26) The remaining part of urban growth—roughly 40 per cent—is a combination of migration and reclassification.
As time passes and as countries become more urban, the proportion of urban growth attributable to natural increase inevitably rises. That is, the higher the level of urbanization in a country, the smaller the pool of potential rural-urban migrants, and the larger the pool of urbanites contributing to natural increase.
Of course, country experiences vary a good deal. In India, a recent assessment of the components of urban growth 1961-2001 found that the share of growth attributable to urban natural increase ranged from 51 per cent to about 65 per cent over the period.(27) Some 65 per cent of current urban growth in Latin America stems from natural increase, despite steep declines in fertility rates, especially in urban areas.(28) China, where migration has recently predominated, is unusual.(29)
Given the greater importance of natural increase and the failure of anti-migration policies, it seems obvious that fertility decline is much more likely than migration controls to reduce the rate of urban growth. Since high fertility in rural areas often underlies rural-urban migration, lower fertility in both rural and urban areas can decelerate urban growth. Such a reduction would give policymakers more time to prepare for the expansion of the urban population.
Policies that aim to slow urban growth should therefore shift their attention to the positive factors that affect fertility decline—social development, investments in health and education, the empowerment of women and better access to reproductive health services. On reflection, it is surprising how rarely this agenda has influenced policy decisions, as opposed to an anti-migration approach.(30) This topic is taken up in the final chapter of this Report.