migration: internal 3017

parsimonious framework for examining both
aggregate flows of population between two
locations and individual level variations in the
propensity to migrate. In short, the model
argues that migration events result from the
combined influence of three types of factors.
Push factors include undesirable characteristics
in the place of origin that compel population
members to consider leaving the area. Pull fac
tors, in contrast, are those characteristics of a
potential destination that attract migrants to the
area. Following a rational choice framework,
the likelihood of migration is high when the
potential destination offers individuals more
advantages than does the place of origin. How
ever, responses to these relative push and pull
factors are shaped by a third set of factors
referred to as intervening obstacles. In essence,
these intervening obstacles are conditions that
increase the social or economic costs of migra
tion and intervene between the desire to move
and the actual act of migrating. Some interven
ing obstacles, such as a great physical distance
or a high cost of transportation between the
origin and potential destination, may increase
the cost of migration for all potential migrants,
thereby limiting the overall magnitude of popu
lation flow between two locations. Other inter
vening factors, such as the strength of social
ties in the community of origin or destination,
the availability of financial resources, health,
and risk aversion, vary across individuals.
Economic opportunities available in the area
of destination have long been treated as the
primary push and pull factors in migration
decisions and considerations such as relative
employment levels in, and wage differentials
between, the origin and destination areas con
tinue to dominate explanations of many migra
tion flows. However, the pushpull model also
accommodates non economic factors as poten
tial pushes and pulls, including the availability
of housing and other resources, the relative
political or sociodemographic conditions in the
origin and destination, or the location of family
and friends. For many individuals, internal
migration accompanies major life transitions
and represents a tool for attaining higher levels
of education, a better job, or more attractive
social surroundings.
Individual level variations in the response to
various push and pull factors and the strength
of intervening obstacles help to produce
migrant populations that are highly selective
of certain characteristics. For example, internal
migration (especially longer distance migra
tion) is positively associated with education
because, in comparison to those with less educa
tion, highly educated population members are
often in the best position to take advantage of
economic opportunities in the place of destina
tion and tend to have access to both informa
tion about potential destinations and financial
resources to carry out a move. The likelihood
of migrating also varies by age, peaking in young
adulthood when the long term, cumulative
benefits of economic opportunities in another
location are greatest and the obstacles associated
with poor health, social obligations, and eco
nomic investment in the community of origin
are least restrictive. A gender imbalance also
characterizes many migration streams, and indi
viduals who are married and/or have children
are less likely to make a move because the cost of
disrupting the social and economic ties main
tained by family members often outweighs the
pull of another geographical area. These selec
tivity factors depend on the type of internal
migration considered and the amenities in the
origin and destination that potential migrants
must weigh, but all have important repercus
sions for the composition of both sending and
receiving populations.

Although data inconsistencies make cross
national comparisons difficult, there is fairly
strong evidence that the magnitude of internal
migration varies across countries and regions of
the world. Rates of migration are thought to
increase with economic development, but the
percentage of the population relocating each
year varies even among highly industrialized
countries; populations in Japan and European
countries exhibit internal migration rates that
are only one half to two thirds as high as those
in the US, Canada, New Zealand, and Australia.
Perhaps even more pronounced are interna
tional variations in the types of moves that affect
various populations. While moves between rural
areas, from urban areas to rural areas, and within