514 MHR • Unit 5 Population Dynamics
The effect of urbanization is an issue that needs
urgent attention, as the size and number of cities —
and their impact on Earth — increase daily (see
Table 15.3). In 1950, New York was the world’s
only megacity (urban area with over five million
inhabitants). By the year 2000, there were 19 such
cities. Tokyo alone had a population of 26.4 million
and New York, with 16.6 million was only the fifth
largest city. In less developed countries, many
cities are swelling rapidly as a result of migration
and high birth rates. Some rural inhabitants move
to cities because their land is degraded, because
they are forced to look for new opportunities as
large companies take over agricultural production,
or because they are unable to find sufficient
firewood or water. Others come seeking jobs or a
new life. Many find it difficult to locate or afford
housing and end up in crowded settlements where
conditions (such as lack of clean water or
sanitation) make them vulnerable to fire, disease,
and bad weather, as shown in Figure 15.9. In some
of the world’s cities, densities are very high. In
Lagos, Nigeria for example, there are an average
of 5.8 people per room, compared to the North
American average of one or two.Lower density (as shown in Figure 15.10) — that
is, a less clumped, more uniform dispersion pattern
— does not necessarily solve the problems caused
by cities, however. In fact, one of the biggest issues
for North American cities is urban sprawl— a
pattern of scattered, uncontrolled development in
which working, living, and recreational areas are
widely separated. This results in very large, diffuse
cities in which it is necessary to drive from place
to place. Sprawl increases pollution and destroys
farmland, parks, and other open spaces. Today, a
new trend toward smart growthis findingenthusiastic support among city planners.
Communities that bring working and living spaces
into close proximity and provide a variety of
housing options (including some high-density
housing) are preferred. The principles of smart
growth encourage cities to be pedestrian- and
cyclist-friendly, have efficient rapid transportation
systems, and set aside land for parks. Food security
is also viewed as important, and consideration is
given to renewing or ensuring the health of
agricultural land near cities.Figure 15.9Contrast this with a Canadian city such as
Toronto.Figure 15.10A residential area of Toronto. How do living
conditions compare with those in Figure 15.9?Percentage Urban (living in cities)
1950 1975 2000
world
Canada and
United States
more industrialized
nations
less industrialized
nations29.7
64.0
54.9
17.8
37.9
74.0
70.0
26.8
47.0
77.0
76.0
39.9
2030
60.3
84.0
83.5
56.2
Table 15.3
Changes in urbanization occurring throughout the world
(from the United Nations Population Division)