Migration

Migration is a difficult concept to define because it includes people who move for different reasons across different spaces. A migrant can be a person who moves to another city or town within a nation; a refugee who crosses an international border to escape religious or political persecution; a jobseeker who moves to another country for better economic opportunities; a slave who is forcibly moved; or a person displaced by war or natural disaster. Demographers lack a single, operational definition for migration because it occurs under different conditions.

The causes of migration are related to the specific contexts in which they take place. First, the composition of migration streams are characterized by structural forces such as the global economy. Second, sociocultural differentials (gender, class, caste, etc.) have important implications for individual mobility.

Because migration occurs under different circumstances, the demographic implications for receiver populations change accordingly. For example, when large numbers of rural residents migrate to cities, infrastructure problems may arise in urban areas.

Given the variation possible in the migration process, all migrants cannot be analyzed with the same theoretical framework. However, although heterogeneous factors make a universal definition impossible, in general, migration is a process in which an individual or a group shifts their residence from one population (or place) to another. Apart from its spatial dimension, migration also implies the disruption of work, schooling, social life, and other patterns. A migrant is someone who breaks off activities and associations in one place and reorganizes their daily life in another place. A move within the same area is considered mobility, not migration, because the mover can continue day-today life (keep the same job or school, shop at the same stores, and socialize with the same people) without significant disruption (Weeks 1999).

Most demographers argue that migration must involve an essentially permanent territorial shift in residence to be distinguished from mobility. Hence, travelers and commuters are excluded from migration studies because they move across boundaries on a temporary basis and because their movement does not generally cause major change in any population. Categorizing movers strictly in terms of the permanence of their move can be problematic, however, because this method tends to disregard the social context of population movement. Temporary moves are typically absent from the census, and therefore do not register in demographic terms. In this perspective, a software engineer who makes a permanent move from San Francisco to Los Angeles is classified as a migrant, while a Mexican arriving in California as a seasonal agricultural laborer is not. However, the agricultural laborer's move is probably the most socially significant given language barriers, culture shock, and race discrimination encountered.

Just because a mover is not measured as a member of a population does not mean that their movement has had no measurable social impact on populations. Under the United States's bracero program (a system created in 1942 to help solve U.S. agricultural labor shortages), for example, the number of temporary Mexican laborers reached a point that U.S. policy makers reacted with mass deportations and the creation of a restrictive immigration act meant to keep Mexicans out. This policy created severe unemployment problems in Mexico, whose economy was not strong enough to reabsorb these workers. Hence, the program that previously encouraged mobility into the United States contributed to Mexican poverty after it was terminated in 1964. Even though they would not be counted as migrants, the mobility of Mexican agricultural workers left a deep impression on the Mexican economy, and it initiated changes to U.S. immigration policy.