This year represents a turning point in human geography. For the first time in history, there are more people living in cities than in rural areas.

Rural-urban migration is directly linked to the development process of countries. The significant social, economic and political consequences of population changes make it vital to understand how the distribution of people between rural and urban areas evolves over time.

Although the Asian and the Pacific region, along with Africa, is still one of the least urbanized regions of the world, its urban population has been growing at the fastest pace during the last decade and a half. In 1990, 33 per cent of the population of Asia lived in urban areas, compared with 41 per cent today. The fastest influx of people from rural areas to cities has occurred in ASEAN countries, where the urbanization rate rose from 32 per cent in 1990 to 45 per cent in 2006.

Figure 2.1 Index of change in the urbanization rate in the regions of the world, 1990-2006

Urbanization has been an integral part of the rapid economic growth experienced by Asia and the Pacific in recent decades. Rural-urban migration in middle-income countries increased by 12 percentage points over the last decade and a half, mobilizing the labour force needed in these expanding economies.

In 1990, just under half the population of ASEAN member countries Malaysia and the Philippines lived in urban areas; by 2006, that number had reached about two thirds. Over the same period, the proportion of Indonesians living in cities increased from less than one third to almost half. The urbanization rate also increased considerably in China, the Islamic Republic of Iran and Turkey, among others.

The Central Asian countries and the landlocked developing countries were the only subgroups that experienced a decline in the urban population, by 2 percentage points between 1990 and 2006. The fall in the urbanization rate of the Central Asian countries is partly due to international migration, which is covered in the next section.

Figure 2.2 Index of change in the urbanization rate in selected Asian and Pacific country groupings, 1990-2006

Although urbanization has contributed to economic growth, it has also driven up urban poverty. This phenomenon is particularly evident in heavily populated slums characterized by substandard housing and poor access to basic services.

In Asia and the Pacific, two out of five urban dwellers live in slums, compared with three out of five in Africa.Still, the share of the urban population living in such conditions, at 44 per cent, is notably higher than the 33 per cent prevailing in Latin America and the Caribbean.

The share of the urban population living in slums in ASEAN countries has decreased by 10 percentage points in just over a decade, faster than anywhere else in the Asian and the Pacific region. In Cambodia and the Lao People's Democratic Republic, however, the proportion of urban dwellers living in slums has remained constant, in contrast with the other ASEAN countries.

Riding on the strength of economies that boomed for most of the 1990s, the Republic of Korea and Thailand are two countries that have achieved impressive reductions in the number of urban slum-dwellers. Other countries in the region, however, have fared quite differently.

In least developed countries that are members of SAARC, there are continuously large numbers of people living in slums. In Afghanistan, 99 per cent of the urban population lives in slums, and Nepal and Bangladesh continue to have high proportions - 92 and 85 per cent, respectively - of the urban population living in slums, although they have had some success in containing the problem.

Figure 2.3 Share of slum population in urban areas in selected Asian and Pacific countries, 1990 and 2001

Whether they are a consequence or a cause of high population density, large slum settlements in Bangladesh make the country one of the 10 most densely populated countries in the world.

The Asian and Pacific region has the second highest population density in the world after Europe.It is more than twice the level of Africa and close to three times that of Latin America and the Caribbean.Population density in Africa, however, increased by over 48 per cent between 1990 and 2005, a much faster pace than the 23 per cent increase registered in Asia and the Pacific.

Macao, China, has the highest population density not only in the region, but in the entire world, at 16,934 persons per square kilometre. In the region, it is followed by Hong Kong, China, and Singapore, which both have over 6,500 persons per square kilometre.

In Asia and the Pacific, the SAARC member countries and the least developed countries especially have become more densely populated; as groups, they have the highest population densities in the world. The SAARC region has a density of 300 people per square kilometre, compared with 126 in the ASEAN region, and 18 in the Central Asian countries - equivalent to the population density of North America.

Figure 2.4 Population density in selected Asian and Pacific countries/areas, 1990 and 2006