• Editors' Summary
• Credits

1. An Urban Future
• Developing World Urbanizing
2. The Urban Poor
3. Pollution and Health
4. Impact on the Environment
5. Making Urban Areas Work

• Figures
• Tables
• Side-bars
• Bibliography

• Developing countries face fastest urban growth
• Why urban areas are growing
• The poor have greatest health risks
• Heavy ecological footprints
• Improving urban governance
• Assuring water and sanitation
• Mumbai cleans up

• POPLINE
• Media/Materials Clearinghouse
• Other issues
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Published by the Population Information Program, Center for Communication Programs, The Johns Hopkins University Bloomberg School of Public Health, 111 Market Place, Suite 310, Baltimore, Maryland 21202, USA

An Urban Future

The world is near a historic turning point. Within four years half of the world’s population will be urban. At that time, the projected urban population of 3.2 billion will be larger than the entire global population in 1967, just 40 years earlier. (For the definition of “urban,” see side-bar, Defining "Urban".)

Urban areas are gaining an estimated 67 million people per year—about 1.3 million every week (131). By 2030 about 5 billion people are expected to live in urban areas—60% of the projected global population of 8.3 billion (131) (see Figure 1).

Over the next 30 years virtually all population growth will take place in urban areas of developing countries (see Figure 2). The urban population of developing countries is projected to grow at an average annual rate of 2.4%, twice the overall annual population growth rate of 1.2% in the developing world (131). Although the urban population of developed countries also will grow faster than their total population, and the developed world will remain far more urbanized than the developing world, urban growth in developing countries is more rapid and, in absolute numbers, much greater.

Large cities have existed for centuries—for example, present-day Xi’an, China, (ancient Changan) had 800,000 inhabitants as long ago as 750 AD, and ancient Baghdad reached over 1 million population between 775 and 935 AD (23). It was not until the industrial revolution in the late 19th century, however, that accelerated population growth and migration sped the growth of cities to historic new levels (39). Between 1950 and 2000, primarily reflecting population trends in developing countries, the world’s urban population more than tripled, rising from 750 million to 2.9 billion (131).

Photo: D. Hinrichsen

Tokyo—world’s largest urban area. In the near future, the developed world will remain more urban than the developing world, but urban growth in developing countries will be more rapid and, in absolute numbers, much greater.

In the next 30 years the urban population of developing countries is projected to double, from just under 2 billion in 2000 to nearly 4 billion by 2030. In contrast, the urban population of developed countries is projected to increase hardly at all—from 900 million in 2000 to 1 billion in 2030. The developed countries are already 75% urban (131).

As the developing world’s population grows, the number of big cities will grow substantially. In 2000 there were 388 cities in the world with 1 million or more residents. By 2015 there will be a projected 554 such cities. Of these, 426—over three-quarters—will be in developing countries. The United Nations (UN) coined the term “megacities” initially to describe cities with 8 million or more inhabitants; the UN’s present threshold for megacity status is 10 million. Currently, the UN lists 17 megacities, all but 4 in developing countries. By 2015, the UN projects, 21 cities will have at least 10 million residents (131) (see Table 1).

Big cities capture attention. Still, most of the world’s urban population lives in smaller urban settlements, not the largest urban agglomerations. In 2000 about 37% of the world’s urban population lived in cities of 1 million or more; 53% lived in urban centers with fewer than 500,000 inhabitants. The UN projects that the largest share of the increase in the urban population through 2015 will be in such smaller urban areas, reflecting both population growth and reclassification of rural areas to urban (131) (see Figure 3).

Differences within countries. Large differences in urban patterns exist within countries. Urban areas range from large cities to small market towns. Generalization about urban areas is often difficult because each urban center has its own unique social, political, and economic setting that helps shape its future growth and development. In Latin America and the Caribbean, for instance, urban areas range from large cities with substantial economic and political importance, such as São Paulo, Brazil, and Mexico City, to small urban centers of various sizes, growth rates, and economic bases (132).