As they explore the wide-ranging social, economic, and political implications of the urban transformation, economists are hampered by a limited set of forecasting tools. New research by Population Council demographer Mark Montgomery aims to refine the data by applying new, spatially sensitive methods for estimating and projecting urban populations, paying close attention to where the urban poor are located within and across cities. His findings, summarized in a special section of the journal Science and as a chapter in a forthcoming book on climate change, analyze the health risks and benefits of urban living and dispel some of the assumptions surrounding urban poverty.
Is there really an urban health advantage?
"There's a common belief that urban dwellers are generally healthier than rural residents, in part because there are more health and social services in cities," Montgomery notes. For instance, one analysis of 90 Demographic and Health Surveys found that, on average, the urban populations of poor countries exhibit lower levels of child mortality than their rural counterparts. Similar urban/rural differences surface across a range of health indicators. "However, averages can be a misleading basis on which to set health priorities," Montgomery explains. "Once we break down the data, it is clear that the urban poor often face health risks that are nearly as severe as or even worse than those of rural villagers."
According to Montgomery, who distinguishes between "slum dwellers" and the "urban poor," much more needs to be done to determine the percentage of the urban poor living in slums. For example, one study of urban India found that of all urban households officially classified as poor in 2005, over 80 percent were in nonslum neighborhoods. Also, slums may contain significant percentages of households whose expenditures would put them above the official poverty line. "Without this information, it is not clear whether poverty alleviation programs should target poor places, such as slums, or poor people, who may live in a variety of neighborhoods," Montgomery says.
Montgomery's work attacks another myth: that most urban residents live in huge urban agglomerations, or megacities, with populations of more than 10 million. In fact, of all urban residents in cities of 100,000 and more in the developing world, only about 12 percent, or 1 in 8 urban residents, live in megacities. The majority of urban dwellers live in smaller cities or towns. "The demographic literature tends to overstate the role of very large cities and underemphasize the importance of small- and medium-sized cities," Montgomery concludes.
Natural population growth rate versus migration
When confronted with rapid urbanization, many governments try to expel slum residents and discourage further migration to densely packed urban neighborhoods. This response is likely based on another myth: that migration accounts for most of the urban growth. In developing countries about 60 percent of the urban growth rate is attributable to natural growth--the difference between birth rates and death rates--while the remaining 40 percent is due to migration and spatial expansion. Therefore, a better approach to controlling urban growth might be to promote voluntary family planning programs and work with government health agencies and advocacy groups to improve services to the poorest urban areas, Montgomery suggests.
Urban health risks are often unacknowledged
According to Montgomery, these and other misconceptions have led policymakers to neglect several key areas, especially in the health field. In many countries residents of smaller cities go without adequate supplies of drinking water and minimally acceptable sanitation. Likewise, while rural shortages of health personnel and services have received attention in recent literature, similar shortages also plague smaller cities and towns. Conventional poverty measures also ignore the important factors of crime and violence, risks that threaten many city dwellers. …