Urbanization and Global Change  

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Global Urban Population in Developed and Developing Countries

The human population has lived a rural lifestyle through most of history.  The world’s population, however, is quickly becoming urbanized as people migrate to the cities.  Figure 1 shows the urban population growth between 1950 and the year 2000.  In 1950, less than 30% of the world’s population lived in cities.  This number grew to 47% in the year 2000 (2.8 billion people), and it is expected to grow to 60% by the year 2025.

Figure 1

Developed nations have a higher percentage of urban residents than less developed countries.  However, urbanization is occurring rapidly in many less developed countries, and it is expected that most urban growth will occur in less developed countries during the next decades.  Figure 2 shows the projected growth of the urban and rural populations in developed and less developed countries.

Global urban population in developed and developing countries Global rural  population in developed and developing countries 

Figure 2: Future projections, 1994-2025 (population in thousands)

The definition of an urban area changes from country to country.  In general, there are no standards, and each country develops its own set of criteria for distinguishing cities or urban areas. A city is generally defined as a political unit, i.e., a place organized and governed by an administrative body.  A way of defining a city or an urban area is by the number of residents.  The United Nations defines settlements of over 20,000 as urban, and those with more than 100,000 as cities.  The United States defines an urbanized area as a city and surrounding area, with a minimum population of 50,000.  A metropolitan area includes both urban areas and rural areas that are socially and economically integrated with a particular city. 

Cities with over 5 million inhabitants are known as megacities.  There were 41 in the year 2000.  This number is expected to grow as the population increases in the next few decades.  It is predicted that by the year 2015, 50 megacities will exist, and 23 of these are expected to have over 10 million people.  Table I is a list of the world’s 25 largest cities in 1995.

The World's 25 Largest Cities, 1995


Population (Millions)

Tokyo, Japan 


Sao Paulo, Brazil


New York, USA


Mexico City, Mexico


Bombay, India


Shanghai, China


Los Angeles, USA


Beijing, China


Calcutta, India


Seoul, South Korea


Jakarta, Indonesia


Buenos Aires, Argentina


Tianjin, China


Osaka, Japan


Lagos, Nigeria


Rio de Janeiro, Brazil


Delhi, India


Karachi, Pakistan


Cairo, Egypt


Paris, France


Metropolitan Manila, Philippines


Moscow, Russia


Dhaka, Bangladesh


Istanbul, Turkey


 Lima, Peru


Table I, Source: United Nations, Population Division. World Urbanization Prospects. 1994


Why is the urban population increasing so fast?

The rapid growth of urban areas is the result of two factors:  natural increase in population (excess of births over deaths), and migration to urban areas.  Natural population growth has been covered in other units, and consequently, here we will concentrate on migration.

Migration is defined as the long-term relocation of an individual, household or group to a new location outside the community of origin.  Today the movement of people from rural to urban areas (internal migration) is most significant.  Although smaller than the movement of people within borders, international migration is also increasing. Figure 3 shows the annual net international migration totals and migration rates in the world’s major areas between 1990 and 1995.  Both internal and international migration contribute to urbanization.

Figure 3: Annual net international migration totals and migration rates in the world's major areas, 1990-1995

Migration is often explained in terms of either “push factors” – conditions in the place of origin which are perceived by migrants as detrimental to their well-being or economic security, and “pull factors” – the circumstances in new places that attract individuals to move there.  Examples of push factors include high unemployment and political persecution; examples of pull factors include job opportunities or moving to a better climate. 

Typically, a pull factor initiates migration that can be sustained by push and other factors  that facilitate or make possible the change.  For example, a farmer in rural Mexico whose land has become unproductive because of drought (push factor) may decide to move to Mexico City where he perceives more job opportunities and possibilities for a better lifestyle (pull factor).  In general, cities are perceived as places where one could have a better life, because of better opportunities, higher salaries, better services, and better lifestyles.  The perceived better conditions attract poor people from rural areas. 

In order to better illustrate the causes of rural migration, we will consider policies that have led to migration in many developing countries.  In order to pay foreign debt and to be more competitive in international markets, national governments have encouraged the export of national resources and agricultural products.  Agricultural products (sugar, flowers, coffee, etc.), and primary-sector goods (timber, fish, minerals, etc) become natural resource capital that can be traded to bolster the national economy.  In order to produce agricultural products quickly, efficiently, and for a decent prize, national governments often look to decrease the number of small producers, and turn agricultural production and resource extraction over to larger enterprises, with larger production facilities, and a lower per-unit cost of production.  This trend turns land into a commodity, that can be bought and sold, and it is viewed only in terms of its productive capabilities.  Free market economics pursues economic efficiency to deliver goods at the lowest possible price, and its advocates maintain that any government intervention diminishes this efficiency.  Consequently, they seek to eliminate farm programs such as farm subsidies, cheap credit policies, etc. intended to help the farmer, and to maintain stable prices.  This scenario leaves farmers to shoulder the burden of farming, sometimes with no alternative but to sell their land to a foreign investor or a domestic-owned enterprise, and move to the cities, where the farmer hopes to have a better life.

Other policies reinforce the above scenario.  In this case, in order to boost the production of cheaper goods, governments have maintained artificially low food prices in urban areas.  The strategy here is to maintain urban food prices below market levels to reduce the cost of urban labor and urban life.  This policy has resulted in inadequate compensation of rural producers for the costs they incur to produce food products and thus have aggravated rural poverty.  On the other hand, these policies have also made city life more attractive and pulled them from rural areas.  As a result of these policies, an average of 270,000 rural migrants have been arriving in Mexico City annually over the last ten years, transforming it into one of the largest cities in the world.

International migration includes labor migration, refugees and undocumented migrants.  Similar to rural-to-urban migration, individuals move in search of jobs and a better life.  Income disparities among regions, and job opportunities, are key motivating factors.  The migration policies of sending and receiving countries also play a key role.  The best current estimate from the United Nations Population Fund, indicates that more than 100 million people were living outside their countries of birth or citizenship in 1998.  There is a number of reasons why this figure is rising, but an important one is that the native labor pool in the industrialized countries is shrinking, while the developing world’s workforce is rapidly increasing.  Figure 4 shows the countries with largest stock of migrants in their population, while figure 5 shows the countries whose populations have the largest percentage of migrants.  Today, international migration is at an all-time high.  About 2% of the Earth’s population has moved away from the country of origin. 

Figure 4: Countries with the largest international migrant stock, 1990 (thousands)


Figure 5: Countries with the highest percentage of international migrants in total population, 1990  (percent)


History of U.S. Migration

  • 1840-1850’s Irish/German
  • 1880-1914 South and East Europeans to factory jobs
  • W.W.I limited immigration
  • 1920’s quota system implemented to maintain northern European immigration base
  • Great Depression and W.W.II limited immigration
  • 1965: Elimination of country- by-country quotas - migrant origin shifts to Asia Latin America - ~800,000 persons/yr
    • ~55% family reunification
    • ~15% employees
    • ~15% refugees
    • ~12% other categories

International refugees contribute to the urban migrant population.  The United Nations High Commission for Refugees (UNHCR) reports that most of the 22 million people who came under its wing in 1997 were fleeing from domestic or international conflict.  Figure 5 shows the number of refugees registered by the United Nations between 1960 and 1997.  The Geneva Convention (1951) on Refugees defines refugees as those individuals who migrate because of:“….well founded fear of being persecuted for reasons of race, religion, nationality, membership of a particular group, or political opinion”.

Nations honoring the Geneva Convention have an obligation to determine whether, in fact, individuals will truly face persecution at home.  Excluded are those who fear famine or are pushed out by natural disasters.  The overwhelming majority of refugees come from developing nations, and most of them flee to poor countries.

Figure 6

What are the Problems Associated with Rapid Urban Growth?

The urbanization process refers to much more than simple population growth; it involves changes in the economic, social and political structures of a region.  Rapid urban growth is responsible for many environmental and social changes in the urban environment and its effects are strongly related to global change issues.  The rapid growth of cities strains their capacity to provide services such as energy, education, health care, transportation, sanitation and physical security.  Because governments have less revenue to spend on the basic upkeep of cities and the provision of services, cities have become areas of massive sprawl, serious environmental problems, and widespread poverty.

During the 19th and early 20th centuries, urbanization resulted from and contributed to industrialization.  New job opportunities in the cities motivated the mass movement of surplus population away from the countryside.  At the same time, migrants provided cheap, plentiful labor for the emerging factories.  Today, due to movements such as globalization, the circumstances are similar in developing countries.  Here the concentration of investments in cities attracts large numbers of migrants looking for employment, thereby creating a large surplus labor force, which keeps wages low.  This situation is attractive to foreign investment companies from developed countries who can produce goods for far less than if the goods were produced where wages are higher.  Thus, one might wonder if urban poverty serves a distinct function for the benefit of global capital. 

One of the major effects of rapid urban growth is “urban sprawl"- scattered development that increases traffic, saps local resources and destroys open space.  Urban sprawl is responsible for changes in the physical environment, and in the form and spatial organization of cities.

Developed and less developed countries of the world differ not only in the percent living in cities, but also in the way in which urbanization is occurring.  In Mexico City (950 square miles), as in many other megacities in the developing world, urban sprawl exists as nearly 40% of city dwellers live in the urban periphery in poverty and environmental degradation.  These high density settlements are often highly polluted owing to the lack of urban services, including running water, trash pickup, electricity or paved roads.  Nevertheless, cities provide poor people with more opportunities and greater access to resources to transform their situation than rural areas

In the United States, poorly planned urban development is threatening our environment, our health, and our quality of life. In communities across the United States, sprawl is taking a serious toll.

Consequences of sprawl in the United States

  • Increases traffic

  • Pollutes air and water.

  • Worsens the damage from floods.

  • Destroys agricultural land, parks, and open space.

  • Costs cities and counties millions of dollars for new water and sewer lines, new schools, and increased police and fire protection.

  • Creates crowded schools in the suburbs and empty, crumbling schools in center cities.

Solutions to decrease sprawl

  • Enacting growth boundaries, parks and open space protection

  • Planning for and directing transportation dollars to promote public transportatio.

  • Reversing government programs and tax policies that help create sprawl.

  • Revitilizing already developed areas through measures such as attracting new businesses, reducing crime and improving schools;

  • Preventing new development in floodplains, coastal areas and other disaster- prone areas.

Readings and References:

  • “International Migration: A Global Challenge”, Population Bulletin, Population Reference Bureau, Inc.., Vol. 51, No. 1, 1996
  • Robert Geodes, Ed., Cities in our Future, Island Press, 1997.
  • Samuel P. Hunting ton, The Clash of Civilizations and the Remaking of World Order, Simian and Schuster, 1996.
  • Peter van deer Veer, Nation and Migration, University of Pennsylvania Press, 1995
  • Joel E. Coven, How Many People can the Earth Support?, Norton, 1995.
  • United Nations, International Migration Policies, UN Publication, 1995.
    World Resources  1996 – 1997   :  The Urban Environment
  • www.aag.org, “Global Change and Urbanization in Latin America”
  • www.prb.org, “Human Population: Fundamentals of Growth Patterns of World Urbanization”.



All Materials Copyrighted 2002 University of Michigan