Visualizing Environmental Science

Population and Urbanization 181

occupations that involve harvesting natural resources—

such as fishing, logging, and farming. In urban areas,

most people have jobs that are not connected directly

with natural resources.

Cities have grown at the expense of rural populations

for several reasons. With advances in agriculture, fewer

farmers support an increased number of people. Also,

in many developing countries, a few wealthy people own

most of the land, and poor farmers are denied access

to it. Consequently, people in rural settings have fewer

employment opportunities. Cities have traditionally pro-

vided more jobs than rural areas because cities are sites

of industry, economic development, educational and cul-

tural opportunities, and technological advancements—

all of which generate income.

Cities are urban ecosystems, and scientists study the ef-

fects of humans on the urban environment. This research

focuses on the ecological effects of human settlement

rather than the interactions among humans themselves.

Study of urban ecosystems is complicated because the flow

of energy, water, and other resources into and out of the city

is linked to the flow of money and the human population

(Figure 7.20). Often political power is connected to better

environmental quality of specific (wealthy) neighborhoods.

Every city is unique in terms of size, climate, culture,

and economic development. Although there is no such

thing as a typical city, certain traits are common to city

populations in general. One basic characteristic of city

populations is their far greater heterogeneity with respect

1. Define urbanization and describe trends in
   the distribution of people in rural and urban
   areas.


2. Describe some of the problems associated with
   rapid growth rates in large urban areas.


3. Explain how compact development makes a
   city more livable.

T

he geographic distribution of people in rural
areas, towns, and cities significantly influ-
ences the social, environmental, and eco-
nomic aspects of population growth. During
recent history, the human population has become
increasingly urbanized. Urbanization involves the move-
ment of people from rural to
urban areas as well as the transfor-
mation of rural areas into urban
areas. When Europeans first set-
tled in North America, the major-
ity of the population consisted of
farmers in rural areas. As of 2011, approximately 79
percent of the U.S. population lived in cities.
How many people does it take to make an urban
area or city? The answer varies from country to country.
According to the U.S. Bureau of the Census, a location
with 2500 or more people qualifies as an urban area.
One important distinction between rural and urban
areas isn’t how many people live there but how people
make a living. Most people residing in rural areas have

Population and Urbanization

LEARNING OBJECTIVES

urbanization A pro-

cess whereby people

move from rural areas

to densely populated

cities.

Products and wastes

(outputs)

Waste heat,

greenhouse gases

Wastewater,

water pollution

Air pollution

Solid waste

Goods, services

Natural capital

(inputs)

Energy (fuel)

Clean water

Clean air

Business and

consumer products

Food

Raw and refined

materials for

construction and

industry

/…iÊVˆÌÞÊ>ÃÊ>Ê`ޘ>“ˆVÊiVœÃÞÃÌi“ÊUʈ}ÕÀiÊÇ°ÓäÊ

The human population in an urban environment requires inputs from the surrounding countryside and produces outputs that
flow into surrounding areas. Not shown in this figure is the internal cycling of materials and energy within the urban system.