Globally, more than 4 billion people live in cities. 2. According to the United Nations, 2007 was the first year in which more people lived in cities than in rural regions. 3. Urban population estimates fluctuate due to differences over the precise definition of a "urban area" and what it comprises. For example, a city with a million people will generally be considered urban no matter how much open land it has, while a city of 500,000 people requires some level of development on this land.
The most populous urban areas are also the largest by population, with Beijing having nearly 20% of the global population but 33% of the world's urban residents. Other large urban centers include Delhi; Istanbul; Karachi; Lagos; Mexico City; Mumbai; New York City; Philadelphia; São Paulo; Shanghai; and Tokyo.
Some countries have large urban populations despite not being classified as such by the UN, including Argentina, Australia, Brazil, Canada, Chile, Colombia, France, Germany, India, Indonesia, Italy, Japan, South Korea, Malaysia, Mexico, the Netherlands, Peru, Poland, Russia, Saudi Arabia, Singapore, Spain, Sweden, Switzerland, Turkey, Venezuela, and the United States.
Other countries have large rural populations but only small numbers of urban residents, such as Africa's many small cities and towns. In these places a small number of people may live in a large area, but overall urbanization is low.
The world's urban population climbed to 4 billion in 2016, while the rural population expanded very little to 3.4 billion. According to UN estimates, 54 percent of the world's population resided in cities in 2016. This is expected to increase to 57 percent by 2050.
China had 44% of its population living in cities in 2016, followed by India with 21%. In absolute numbers, China's urban population was 1.3 billion and India's was 500 million.
However, these figures are misleading. The vast majority of those living in Chinese cities are migrant workers who can only expect a bleak future there because they will not be able to afford to return home during their working years.
In fact, there are now more rural than urban residents in several large countries including Russia, Brazil, and Mexico. These are places where economic growth has been driven primarily by industrialization and migration to cities, but not by effective integration of their rural populations.
Even in countries such as Indonesia or Nigeria, where urbanization has been much faster than in China or India, most of the new people moving to cities are from the middle class who can afford to leave their farms behind. They are not needed on the land and so they go to town, building up metropolitan areas that are no longer viable communities for farmers.
According to UN Urbanization Prospects, this will be slightly more than 55% of the global population in 2018. The United Nations numbers on global urbanization are the most extensively used and quoted. However, they are not strictly comparable with previous years or future projections because they are based on a new methodology developed by the United Nations Population Division.
Almost every city in the world is projected to have more people living in them than existing cities. Only three countries - Russia, India and China - are expected to see their existing cities become completely saturated by 2030.
In fact, the only way that current cities can remain fully occupied is if all children grow up with access to high-quality education and health care and if everyone works for at least one year of their life. This would require an unprecedented level of cooperation between cities across the globe. It also goes against human nature - why would anyone work for a single company for a year straight? - but it shows how important it is for humans to cooperate when living in large groups.
Currently, there are two types of cities: capital cities and non-capital cities. A capital city is defined as "a city that contains both legislative and executive branches of government". Most large cities around the world are capital cities, including New York City, London, Tokyo, Beijing, Delhi and Ottawa.
The continent's entire population is expected to reach almost 2.5 billion people by 2050, with around 55 percent residing in metropolitan areas (figure 1). Given that fewer than 10% of Africa's population lived in cities in 1950, this is a substantial growth. Indeed, it would be like adding America's population to that of Europe.
Cities are the engine of progress for both developed and developing countries. In the former, they drive economic development and provide jobs; in the latter, they foster innovation and increase connectivity, which help economies grow.
In addition to being important for their own populations, African cities are also hubs for internal migration within Africa and for immigration to more developed countries. The number of urban residents in Sub-Saharan Africa has increased from 40 million in 1950 to about 250 million today, with most of the growth occurring since 2000.
Urbanization on the scale seen in Africa over the past few decades has profound implications for social, economic, and environmental sustainability. Increasingly large numbers of people moving to cities for work or education lead to overcrowding and lack of affordable housing. Transport systems become overloaded, while pollution increases due to more vehicles on the roads and less efficient fuel combustion technologies. Overall economic activity rises but so does energy consumption, leading to further climate change.
However, there are also positive aspects to rapid urbanization.