The urban population of the world has doubled since 1950 and is likely to do so again before 2000. Large shifts are occurring throughout the world from agricultural activities in rural areas to non-agricultural activities in urban areas, on a scale and at a rate hitherto unknown.
Steps that have been taken to stem the rising tide have been palliatives at best, mainly because they have often been formulated without an adequate knowledge of the causes and consequences of migration. Also, little is known on whether it is possible or desirable to control the flow. The issue is riddled with unanswered questions and, above all, with persistent myths that obscure the search for solutions.
Most of the growth in the world's population is taking place in developing countries and most of the projected increase of 1,000 million people between 1999 and around 2010 is likely to be absorbed by cities in these countries – cities already faced with enormous backlogs in housing and infrastructure development, and struggling with increasingly overcrowded transportation systems, insufficient water supplies, deteriorating sanitation and environmental pollution. In spite of this, people continue to migrate to cities in the hope of a better life, often as a result of the devastation of rural economies by land degradation.
In 1993, 60 million of China's rural workers were moving, mostly from poor central regions to the coastal cities in search of jobs. It is the first large internal migration of the communist era. For decades, residency controls prevented peasants from moving, creating a pool of surplus rural labourers that had grown to 100 million strong.
Major cities in Africa are experiencing rapid growth. Nairobi, Dar es Salaam, Lagos and Kinshasa grew sevenfold during 1950-80, mainly because of rural-urban migration (Johns Hopkins 1998). During 1950-95 the population of Cairo quadrupled from 2.4 million to 9.7 million. Lagos in Nigeria is now even bigger with 10.3 million inhabitants (United Nations Population Division 1997). In 1997, the largest cities in 24 African countries had populations of more than one million each (UNDP 1997), nearly half of them in Western and Central Africa. Rapid urbanization is expected to continue for decades.