184 CHAPTER 7 Human Population Change and the Environment
with populations of 2000 or greater (Figure 7.23). The
percentage of people living in cities compared with ru-
ral settings is greater in highly developed countries than
in developing countries. In 2011, urban inhabitants
comprised 75 percent of the total population of highly
developed countries but only 46 percent of the total
population of developing countries.
Although proportionately more people still live in
rural settings in developing countries, urbanization is in-
creasing rapidly there, by both natural increase (more
births than deaths) and immigration from rural areas.
Each week the world’s cities increase by approximately
one million people!
Currently, most urban growth in the world is occur-
ring in developing countries, whereas highly developed
countries are experiencing little urban growth. As a result
of the greater urban growth of developing nations, most
of the world’s largest cities are in developing countries.
In 1975, 4 of the world’s 10 largest cities—Mexico City,
São Paulo, Buenos Aires, and Calcutta (now Kolkata)—
were in developing countries. In 2007, 8 of the world’s 10
largest cities were in developing countries: Mexico City,
Mumbai, São Paulo, Delhi, Shanghai, Kolkata, Dhaka
(in Bangladesh), and Buenos Aires. By 2025, 8 of the
world’s 10 largest cities will still be in developing coun-
tries, although Karachi, Pakistan, will have made the list,
replacing Buenos Aires (Figure 7.24).
According to the United Nations, almost 400 cities
worldwide have a population of at least 1 million inhab-
itants, and 284 of these cities are in developing coun-
tries. The number and size of megacities (cities with
more than 10 million inhabitants) have also increased.
In many places, separate urban areas have merged into
urban agglomerations, urbanized core regions, each of
which consists of several adjacent cities or megacities
and their surrounding developed suburbs. An exam ple is
the Tokyo–Yokohama–Osaka–Kobe ag-
glomeration in Japan, which is home
to about 50 million people. However,
according to the U.N. Population Divi-
sion, most of the world’s urban popula-
tion still lives in small or medium-sized
cities with populations of less than 1
million.
It is useful to compare urbani zation
in highly developed countries with that
in developing countries. Con sider the
United States as repre senta tive of highlyspace, housing, and businesses. Compact development
makes a city more livable and attractive to people.
Portland, Oregon, provides a good example of com-
pact development. Although Portland is still grappling
with many issues, the city government has developed ef-
fective land-use policies that dictate where and how growth
will occur. The city looks inward to brownfields rather than
outward to the suburbs for new development sites. From
1975 to 2005, Portland’s population grew 50 percent, from
0.9 million to 1.8 million, yet the urbanized area increased
about 2 percent. In contrast, from 1975 to 2005, the popu-
lation of Chicago grew 22 percent, and its urbanized area
increased more than 50 percent due to sprawl.
Although the automobile is still the primary means
of transportation in Portland, the city’s public transpor-
tation system is an important part of its regional master
plan. Public transportation incorporates light-rail lines,
bus routes (many of which feature buses arriving every
15 minutes), bicycle lanes, and walkways as alternatives to
automobiles. Employers are encouraged to provide bus
passes to their employees instead of paying for parking.
The emphasis on public transportation has encouraged
commercial and residential growth along light-rail lines
and bus routes instead of in suburbs.
Urbanization Trends
Urbanization is a worldwide phenomenon. Currently,
51 percent of the world population lives in urban areas
Rural
population19505001000150020002500300035004000450050001960 1970 1980 1990
Year2000 2010 2020 2030Population (millions) Urban population50% in 2008Based on data from Population Reference Bureau.The worldwide shift from rural to urban
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In 2008, a significant milestone was reached as, beginning that
year, over 50 percent of the world’s population now lives in
urban areas. Source: Modified from U.N. Population Division,
Department of Economic and Social Affairs 2003. World
Urbanization Prospects: The 2003 Revision.