The discourse on sustainable development has, over the years, paid very little attention to urbanisation and urban development.

Decades of international and national efforts in agricultural and rural development have not arrested rapid migration into cities. Many still believe that efforts in rural development will have an impact on migration.

This argument forgets the teaching of economic theory, namely, agriculture is a residual employer and as such, sheds its surplus labour.

The problem of rapid and chaotic urbanisation cannot be avoided by administrative means but by strategic settlement plans that would distribute populations in a balanced manner. This issue of balanced economic development is a major factor that needs to inform macro-economic frameworks and development plans.

And in any case, whether we are successful or not in reducing the pace of rural-urban migration is becoming irrelevant. We have reached the stage where most urban growth is due to the natural increase of the existing urban population, not migration per se.

A second trend lies in the dynamics of urban economies that are rapidly changing. The primary source of economic growth of developing countries is increasingly located in towns and cities.

In many countries, industry and services account for an ever-increasing proportion of national income relative to agriculture. A third reason we are facing the urban challenge is misinformed government policies.

There has been a long-standing notion that the urban poor are better off than the rural poor. For decades, development planners, statisticians, and decision makers have confused proximity with access.

We have assumed that by virtue of the fact that slums are often located close to schools, hospitals, and trunk infrastructure, that slum dwellers have access to these services.

Governments are encouraged to review macroeconomic policies that favour investment in pro-poor housing and urban development, not only as a means of addressing the social consequences of rapid urbanisation, but more importantly as a major means of stimulating local economic development.

This review should also include the need for more enabling policies and strategies that help to realise the full potential of the informal economy.

It is recommended that sustainable urbanisation be introduced as a standing item of the agenda for the high-level discussions on sustainable development in the UNCTAD Trade and Development Board.

Dr Tibaijuka is executive director, UN Habitat.