Human Geography

The movement of groups and individuals from one place to another, involving a change of usual residence. Migration is usually distinguished from mobility in general by conventions of spatial and temporal scale. For example, by convention international migration requires crossing a national boundary for an actual or intended period of at least one year. Residential mobility, by contrast, may consist of a short-distance move between properties in the same city.

Typologies of migration differentiate between internal and international migration, and the two forms are usually studied separately. Looked at historically, however, the movement of people long predates nation-states; homo sapiens left Africa some 150,000 years ago. Geographers are interested in inter-regional, rural-urban, and urban-rural movements, especially in societies with low birth and death rates where migration is often the major cause of population change (see counter-urbanization). In 2008, about 3 per cent of Americans moved to another county, for example, and in China, it is estimated that there were 140 million migrants, mostly from rural to urban areas (Fan 2008).

The major focus of current geographical work, however, is international migration. It is estimated that there were 215 million people living outside their country of birth in 2010, around 3 per cent of the world’s population. But this surprisingly low number has disproportionate effects on the places and countries linked by flows, economically, socially, culturally, and—increasingly—politically. This type of migration is further classified by time, differentiating temporary (or short-term), permanent (or long-term), and circular (including seasonal) forms. Whereas permanent migration was once considered the norm—especially during the era of colonial settlement in the 19th century—it is now recognized that growing numbers of people are implicated in migrations at a variety of spatial and temporal scales. Transnational migrants may live in two places at once, or at least shuttle between them on a regular basis in addition to sustaining meaningful inter-connections. Further distinctions are often made between legal and illegal immigration.

Beginning with the work of Ravenstein, geographers and others have sought to explain and model migration. An elementary dichotomy between forced and voluntary migration has proved difficult to sustain analytically, not least because of the rise in human trafficking. Can children accompanying adults, for example, be said to choose to move? The globalization of human flows has not only drawn in more counties and regions into the world migration pattern, but it has also eroded once-basic division between sending (or home, origin) and receiving (or host, destination) countries. Many are now both; the Russian federation is in the top three emigration and immigration countries. Rather than explain migration in terms of ‘push’ factors at an origin and ‘pull’ factors at a destination, the metaphor of a revolving door may be more appropriate. In a widely cited textbook, Castles and Miller (2009) discuss three broad kinds of explanation: first, neoclassical economics, focusing mainly on the individual level (see Todaro model); second, historical-structural, including world systems theory; and third, migration-systems theory, including a concentration on the role of social networks (see also Massey 1999 for a more elaborate list of theories). The observation that migration flows along distinct ‘corridors’ (e.g. Mexico–USA, Turkey–Germany) fits with this theory. But, compared with the 1960s and 1970s, when geographers applied various spatial interaction models (see gravity model) to migration, there is now less discipline-specific research on the causes and consequences of migration.

Geographical research on migration is far-reaching, covering both historical past and the present (King et al. 2010). Once considered a peripheral subject in social sciences, the study of migration is increasingly deemed central. Paradoxically, given the changes in personal and social mobility associated with globalization, it is ever harder to distinguish migration from the greater register of flows (King 2002); are backpackers migrants? There is a clear trend towards studying migrants, their experiences, biographies, families, emotions, etc., as contrasted with the demographic fact of migration. Migration is generally a selective process, by age, skill, gender, race, class, and health, and it may also be implicated with critical lifecourse events. Recent research foci have included the impact of climate change, the migration-development nexus, children’s migration, international student migration, and the heightened security and surveillance directed at moving bodies of all kinds. See also immigration; iom.