Urban growth isn't necessarily streaming in from the countryside.
The stats are pretty clear: the world's population is increasingly concentrating in urban areas. A recent report from the United Nations estimates that the global urban population will grow from its 2011 level of 3.6 billion people to more than 6.3 billion by 2050. Most of that growth is projected to happen in less developed countries.
As we reported when that report was released in April, much of the growth in developing countries is expected to happen in Africa:
The most substantial growth is expected to occur in Africa. In 2011, urban residents in Africa made up about 11 percent of the world's urbanized people. By 2050, they will represent 20 percent. Between 2011 and 2030, Africa's urban population is expected to grow at an annual rate of 3.09, the highest in the world.
So it was somewhat surprising to see this article from AlertNet, which suggests that in many of the biggest cities in Africa, more people are moving out than are moving in.
Deborah Potts, a demographer from Kings College London who studies urbanization in sub-Saharan Africa, says that more people are moving from urban areas to rural ones in countries like Ivory Coast, Mali, Zambia and Central African Republic. She says these "counter-movements" are the result of the severe shortage of jobs in many of Africa's teeming cities. This out-migration has slowed the expected growth rate even of cities like Lagos, Nigeria, currently the most populous urban area in Africa.
Cities in Africa are still growing, Potts says, just not necessarily from the rural-to-urban migration patterns seen in other developing countries like China and India in recent decades.
Better education for women, reductions in child mortality and higher incomes have driven falling birth rates in many parts of the world, particularly in towns and cities. But urban Africa, with its shortage of jobs and persistently high rates of child and maternal mortality, has not seen the declines expected.
Today in Africa, "most urban population growth comes from natural increase in the cities and not from migration. This comes as a surprise to most people," Potts said.
Asia - not Africa - remains the world's fastest urbanising region, she said, noting that Africa "may remain primarily rural for decades", in part because of a lack of employment opportunities in cities.
So while natural increase may be what's driving urban growth in these African cities, it will also be driving growth in Africa's rural areas. The masses may not be the same in the rural areas as they are in the urban areas, but if Potts is correct, there could be a strong urban-rural dichotomy in Africa for a long time coming.
Top image: Miners pan for gold in a rural area in Mali. Credit: Joe Penney / Reuters