Applying Population Ecology: The Human Population - Environmental Science - page 142

Third, many people migrated from the North and
East to the South and West. Since 1980, about 80% of
the U.S. population increase has occurred in the
South and West, particularly near the coasts. California
in the West, with 34.5 million people, is the most popu-
lous state, followed by Texas in the Southwest with
21.3 million residents. This shift is expected to
continue.
Fourth, some people have migrated from urban and
suburban areas back to rural areas since the 1970s, and es-
pecially since 1990. The result is rapid growth of
exurbs , vast sprawling areas that are not related to cen-
tral cities and have no center.
During these shifts in the last century, the quality
of life for most Americans improved significantly
(Figure 7-5). Since 1920, many of the worst urban envi-

Case Study: Urbanization in the United States
Eight of every ten Americans live in urban areas,
about half of them in sprawling suburbs.
Between 1800 and 2005, the percentage of the U.S.
population living in urban areas increased from 5% to
79%. The population has shifted in four phases.
First, people migrated from rural areas to large central
cities. Currently, three-fourths of Americans live in 271
metropolitan areas (cities with at least 50,000 people),
and nearly half live in consolidated metropolitan areas
containing 1 million or more residents (Figure 7-15).
Second, many people migrated from large central cities
to suburbs and smaller cities. Currently, about 51% of
Americans live in the suburbs and 30% live in central
cities.

Seattle

Minneapolis

Portland

Boise

Boston

Chicago

Salt Lake
City

New York

Provo

Kansas
City

Denver

Cincinnati

Washington, D.C.

St. Louis

San Francisco
Fresno Nashville

Charlotte

Las Vegas

Tulsa Raleigh

Los
Angeles

Memphis

Wilmington

Phoenix

Atlanta

Dallas Myrtle Beach

San Diego

Tucson

Houston

Austin

Orlando

Laredo

Naples

McAllen

Figure 7-15 Major urban areas in the United States based on satellite images of the earth at night that show
city lights (top). About 8 out of 10 Americans live in urban areas that occupy about 1.7% of the land area of the
lower 48 states. Areas with names in white are the fastest-growing metropolitan areas. Nearly half (48%) of
Americans live in consolidated metropolitan areas with 1 million or more people that are projected to grow and
merge into huge urban areas shown as shaded areas in the bottom map. (Data from National Geophysical
Data Center/National Oceanic and Atmospheric Administration, U.S. Census Bureau)