3018 migration: internal

urban areas are common in many countries,
internal migration patterns in developing
nations are generally dominated by high rates
of migration from rural to urban areas. As a
result of this migration, combined with rapid
population growth, the number of people living
in urban areas has increased sixfold in Asia,
Latin America, and the Caribbean, and by over
nine times in Africa in the second half of the
twentieth century. Thus, despite the counter
vailing force of rapid natural increase in rural
areas, the percentage of the population residing
in urban areas is expected to surpass the
50 percent mark in virtually every region of the
world by 2025. Reflecting the importance of this
urban transition, much of the research on inter
nal migration in developing countries has
focused on cross national variations in the pace
of rural to urban migration, the uneven pattern
of urban development, and the consequences of
rapid urbanization for future economic develop
ment, the provision of city services, and envir
onmental conditions in developing nations.
Consistent with Wilbur Zelinskys (1971)
migration transition thesis, patterns of internal
migration tend to be somewhat more diverse in
economically developed parts of the world
where levels of urbanization are already high.
In the United States, for example, researchers
have focused on a wide range of major internal
migration processes, including both historical and
contemporary shifts in patterns of interregional
migration, ongoing metropolitan decentraliza
tion, and migration between demographically
and economically differentiated neighborhoods.
Research on migration between states and
regions within the US documented the west
ward expansion of the population during the
early decades of the countrys history, the con
centration of population in the urban centers of
the Midwest and Northeast as migrants from
surrounding rural areas and other regions of
the country were attracted to the economic
opportunities available during industrialization,
and then the reversal of these migration flows
after World War II, with the original industrial
core of the Northeast and Midwest losing both
economic prominence and migrants to southern
and western states. In addition to tracking these
basic migration patterns and documenting their
efficiency in redistributing the population,
social scientists have investigated the causes of
these population shifts, giving rise to debates
about the relative effects of aggregate adjust
ments to changing ecological conditions and
the political and economic manipulation by cor
porate interests to spur competition between
regions and cities for increasingly mobile capital.
Common to most theoretical arguments is
the acknowledgment that patterns of internal
migration continue to respond to the distri
bution of economic opportunities. However,
in the context of a post industrial, electronic
economy, many researchers have also argued
that non economic conditions are increasingly
important in determining migration patterns.
According to these arguments, the push and
pull factors that shape patterns of internal
migration in the US have become increasingly
complex in recent decades, producing migration
flows to various regions and states that differ
sharply in terms of their sociodemographic
composition.
Recent patterns of internal migration within
regions of the US have been characterized by
cycles of decentralization. As in most nations,
American cities represented the central nodes
of economic activity during the initial stages of
industrialization and experienced explosive
growth as a result of in migration. In the US,
however, the process of population decentrali
zation away from the urban core began almost
immediately after the birth of US cities. After
World War II, a combination of consumer pre
ferences, demographic forces, and federal pol
icy accelerated the pace of migration from
central cities into suburban counties of metro
politan areas and set into motion a process
of decentralization that continues today with
the perpetual expansion of low density sub
urban fringes, the extension of metropolitan
areas into surrounding counties, and residen
tial development of non metropolitan counties.
While suburban growth is largely the product
of internal migration flows that cover fairly
short distances from central cities to suburban
counties of metropolitan areas the purported
impacts have been dramatic, including eco
nomic disinvestment and the concentration of
poverty in central cities, the entrenchment of
residential segregation by race, metropolitan
political fragmentation, the erosion of civic
engagement, the loss of land available for agri
culture, and environmental degradation.