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Causes of South-South Migration and Its Socioeconomic Effects

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Causes of South-South Migration and Its Socioeconomic Effects

A market in South America, where Colombians account for the largest number of intraregional migrants.

The extent of migration between developing countries, called South-South migration, and the issues surrounding it remain poorly understood. Part 1 of this series examined data on South-South migration and South-South remittances.

In Part 2, the focus is on why migrants from one developing country go to another developing country, and what kinds of socioeconomic effects such movements have on both migrants and nations.

Determinants of South-South Migration

Income, proximity, and networks are the major drivers of migration from developing to industrial countries. As South-South income differentials are relatively modest, proximity and networks likely have a proportionally greater impact, while the role of income is more complex.

Motivations for South-South migration also include seasonal patterns and flight from ecological disasters or civil conflict. Other motivations, not recorded in the migration stock data in Part 1, include transit to the North and petty trade. Agreements among countries have had comparatively little impact on South-South migration.

Proximity. Almost 80 percent of identified South-South migration takes place between countries with contiguous borders (see Figure 1). A large share of migration between countries with noncontiguous borders goes to countries that are relatively close, according to analysis by economist Andrew Rose.

The costs (financial, social, and cultural) of migrating to nearby countries are likely to be lower than those of moving farther away. Because many South-South migrants lack adequate travel documents, they are restricted to overland migration. And ethnic, family, and religious ties link communities across borders, particularly in Africa, where colonial boundaries straddled tribal groups, but also in other parts of the world.

Networks. Ethnic, community, and family ties reduce the costs and uncertainties involved in migration. In Africa, migrant networks play a critical role in magnifying outflows once migration is underway. In some areas, migrant diasporas are longstanding: the arrival of significant number of Swazis, Tswanas, and Basothos in South Africa stems from movements of tribal groups in the 19th century.

Evidence for the impact of networks can be found in linkages between nationalities and jobs. For example, Poles in Hungary have frequently worked in mining and construction, while Slovakian women often worked in textiles.

In the Russian Federation, studies show that foreign workers in building, industry, and transport often come from Ukraine. Migrants from Azerbaijan, China, and Vietnam often work in trade, and Chinese often work in agriculture.

Figure 1. Number of Migrants Who Move to Countries with and without Common Borders
Source: Authors' calculations based on University of Sussex and World Bank bilateral migration data, and Rose (2004).

Income. Income differences between countries have some influence on South-South migration. The clearest example is seen in middle-income countries that have substantial numbers of immigrants from nearby low-income countries. For example, Argentina, Chile, and Venezuela attract migrants from Bolivia, Paraguay, and Peru; Malaysia draws migrants from Indonesia; and South Africa attracts people from Lesotho, Mozambique, Namibia, and Zimbabwe.

Given the extreme poverty in many low-income countries, substantial migration flows also occur among low-income countries of different income levels. Consider, for example, migration from Burkina Faso, Mali, and Niger to Cote d'Ivoire and Ghana, and from Bangladesh and Nepal to India.

But the available data indicate that differences in country income play a limited role in South-South migration. About 38 percent of identified South-South migrants come from countries with higher incomes than their host country. However, of the total stock of identified migrants from higher-income countries, just over half can be attributed to the breakup of the Soviet Union, while another, indeterminate, share left due to conflict or natural disaster.

Of the migrants from lower-income countries, most go to countries with incomes only slightly above that of their home country. Only about 20 percent of identified South-South migration from lower- to higher-income countries is to countries with very large differences in income (that is, countries in the top 40 percent of income differences with the sending country).

Examining migration patterns according to income groups, we estimate that more than two-thirds of South-South migrants from low-income countries are in other low-income countries. The corresponding figure for middle-income countries is 93 percent (see Table 1).

Differences in country incomes are likely much greater, on average, for migrants traveling outside their native region than for intraregional migration, partly because larger income differentials are required to overcome higher costs associated with traveling over greater distances (geographic and cultural).

In the lowest-income regions (sub-Saharan Africa and South Asia), almost all identified intraregional migration from lower- to higher-income countries is to countries with only slightly higher income levels. The other regions show a larger share of intraregional migration going to countries with significantly higher income, reflecting the major middle-income migration poles of Argentina, Jordan, Malaysia, the Russian Federation, Thailand, Venezuela, and parts of Eastern Europe.

Table 1. Migration Patterns by Income Classification (millions of migrants)

Migrants in:
  High-income OECD countries High-income non-OECD countries Low-income countries Middle-income countries Total Intra-income group as percent of South-South
Migrants from:            
Low-income countries 11 6.6 16.2 7.9 41.8 67.3
Middle-income countries 49.9 9.6 2.2 30.28 91.9 93.3
High-income countries 28.7 1.1 0.3 3.81 34  
Total 89.6 17.3 18.7 42 167.6  

Source: University of Sussex and World Bank. These data include only identified migrants — 60.7 million in the South and 106.9 million in the North — for which both source and destination are known. These exclude 4.7 million migrants in the South and 4.9 million in the North for whom the source country is not known, as well as 12.7 million migrants in 37 countries in the South and 0.8 million migrants in 6 countries in the North about whom the respective censuses offer no information.

Seasonal migration. Regardless of income differences, seasonal migration may occur as individuals take advantage of weather patterns. There also is some evidence, largely from studies of internal migration, that migration between areas of similar income levels can help families diversify income sources and thus reduce risk.

Thousands of Nepalese farmers cross into northeast India during planting and harvesting seasons. In West Africa, temporary migration may be the principal form of cross-border labor mobility, owing to regional variations in the seasonality of agricultural production.

Although seasonal migration also occurs in South-North migration, it may be more prevalent in South-South migration because borders are more porous and agriculture weighs more heavily in the economy. By contrast, temporary migration divorced from seasonal agricultural employment is common in both South-South and South-North migration.

Transit. Some developing countries receive migrants in transit to industrial countries. Mexico has become an important destination for migrants from Central America, both as a place to settle and as a temporary stop on the way to the United States.

The Czech Republic and Poland are important transit countries for migrants wishing to enter Germany. West African migrants travel to Cape Verde, The Gambia, and Guinea to obtain false documents en route to Europe. Turkey and North African countries serve as transit points for migrants to southern Europe.

Middle-income developing countries also serve as a springboard for professionals from lower-income countries bound for destinations in the North, as exemplified by nurses from Ghana who work in South Africa before migrating to Canada, the United Kingdom, or the United States.

Petty trade. Individuals also cross borders to sell small amounts of goods as informal street traders, for example; such individuals are not strictly classifiable as migrants. Longstanding arrangements, such as the 1950 agreement between India and Nepal allowing free passage and trade, can operate with little monitoring and by all accounts cause no trouble.

For many years, traders from Mozambique and other locations in southern Africa have regularly crossed into South Africa, usually on visitor visas that do not permit trading. Angolans cross into Namibia for various reasons, including trade. What is called "suitcase trading" by migrants from neighboring countries in the north, while not constituting migration in its strict sense, has reached huge volumes in Turkey.

In Latin America, the economic crises of the 1980s increased the number of self-employed migrants and of migrants working in services and commerce. Twice a week, a key border town in the Dominican Republic allows Haitian traders access to markets without immigration inspection.

Conflict and disaster. Migrants escaping from war usually go to other, neighboring developing countries, often as a first step in seeking asylum. In fact, most refugees and asylum seekers are located in developing countries. At the end of 2005, the number of refugees in developing countries was three-and-a-half times that in developed countries according to the United Nations High Commissioner for Refugees (UNHCR).

The number of UNHCR-recognized refugees and asylum seekers fell from 13 million in 1997 to 9 million in 2005 (see Table 2). Although UNHCR data do not include all people displaced over international borders because of conflict, the decline in refugees and asylum seekers does reflect some reduction of political conflicts in Africa, where the number of refugees fell from 5.4 million in 1990 to about 3 million in 2005.

Civil violence also has been a major driver of migration in Latin America, where Colombians account for the largest number of intraregional migrants. The rise in the number of international migrants in Latin America during the 1980s, and the decline in the 1990s, was mainly attributable to movements of refugees and displaced persons during the conflicts of the 1980s and their return once peace was restored.

Table 2. Number of UNHCR-Recognized Refugees and Asylum Seekers (in millions), 1997 to 2005

  1997 1998 1999 2000 2001 2002 2003 2004 2005
Asylum seekers 1.0 1.0 1.0 1.1 1.1 1.1 1.0 0.8 0.8
Refugees 12.0 11.5 11.7 12.1 12.1 10.6 9.7 9.6 8.4
Total 13.0 12.5 12.7 13.2 13.2 11.7 10.7 10.4 9.2

Source: UNHCR.

Ecological disasters sometimes provoke South-South migration. The Red Cross estimated that, in 1999, environmental disasters displaced as many as 25 million people, including those displaced within countries, and the number is likely to grow.

This 25-million figure covers a spectrum of issues with varying mixtures of human and natural causes, including dam construction, pollution (the degradation of the Niger delta due to oil spills), desertification (e.g., in China, Libya, Morocco, and Tunisia), soil erosion (Turkey), and drought (the Sahel).

Regional and bilateral agreements. Among developing countries, these types of agreements have made little progress in easing constraints on migration, compared with the European Union's guarantee of mobility and the treaty between Australia and New Zealand.

Some progress has recently been achieved. Nationals of Mercosur (Argentina, Brazil, Paraguay, Uruguay, and Venezuela) theoretically have access to legal residence in any other member state — and Argentina's new immigration law obliges state authorities to simplify legal residence for foreigners in line with Mercosur requirements.

The common East African passport is in use by Kenyans, Ugandans, and Tanzanians, and visa-free movement of persons within West Africa is occurring under the Economic Community of West African States (ECOWAS). But the provision of common travel documents does not guarantee legal residence or work rights. In addition, the lack of capacity to issue, register, and monitor documents at land borders has hampered the process.

In addition to agreements, consultation processes have emerged to consider regional cooperation on migration issues. Examples include the Dakar Process in West Africa, the Bali Process in Southeast Asia and the Pacific, the Regional Consultations on Migration in Central and North America (the "Puebla Process"), the South American Conference on Migration (the "Lima Process"), and the Pacific Immigration Directors Conference (PIDC). Although the majority are focused on enforcement and security issues, these processes are shifting to include more facilitative approaches to migration.

Bilateral migration agreements and memoranda of understanding are becoming more common among developing countries. Examples include the myriad bilateral agreements between Malaysia and Thailand, Vietnam's agreements with Eastern Europe and some neighboring countries, Argentina's agreements with Bolivia (1999) and Peru (1999), and several agreements in Central Asia that account for most legal cross-border labor flows.

Socioeconomic Dimensions of South-South Migration

Analyzing the welfare implications of South-South migration is fraught with difficulties for two reasons: the tentative nature of the migration data and insufficient information on economic and social conditions in many developing countries.

The following section reviews selected topics on the socioeconomic dimensions of South-South migration, including wages, irregular migration, health, gender, trafficking, and unstable migration flows.

Wages. It is difficult to judge the impact of migration on labor-market conditions in destination countries. In industrial countries, estimating the relationship between migration and wages is difficult principally because it is hard to control for internal and external factors affecting wages — migration affects wages, but wage levels also affect migration decisions.

In most developing countries, the basic data required to gauge the impact of migration on the labor market — time series of migration flows or stocks and wage data — are lacking. Thus, most analyses are based on anecdotal evidence; some are wholly unsupported.

To gain insight into the differential impact of South-South versus South-North migration, we used two model-based simulations of an increase in migration.

The first simulation assumes that the number of workers migrating from developing to industrial countries increases by an amount equal to 3 percent of the labor force of industrial countries by 2025 (a rise of 14.2 million migrant workers).

The second assumes the same increase in the number of migrants from developing countries, except that they go to other developing countries. (New migrants are allocated in proportion to the stock of existing migrants.)

For South-North migration, the new migrants enjoy a gross increase in wages (before accounting for any rise in taxes or subtracting remittances) of more than 2,300 percent (see Table 3). For South-South migration, where wage differentials between origin and destination countries are much smaller, the new migrants experience a comparably small (albeit still significant) increase of 60 percent.

Table 3. Change in Wages in Destination Countries from Increased South-North and South-South Migration (percent change from baseline)

  South-North migration South-South migration
New migrants 2,314 60
Natives -0.7 0
Existing migrants -13 -6.6

Source: Authors' calculations.

The greater rise in wages for South-North migrants should be adjusted to more closely approximate the welfare gains involved. South-North migrants experience much larger increases in the cost of living than do South-South migrants, reducing the relative welfare advantage obtained from South-North migration.

In general, higher prices in rich countries imply that welfare gains for migrants from developing countries should be divided by three, on average. Assuming that South-North migrants' welfare gains are reduced by this ratio and that South-South welfare gains are not adjusted, South-North migration would still be more than 10 times more profitable than South-South.

Two other considerations that are more difficult to quantify reduce the welfare advantage of South-North relative to South-South migration. First, many South-North migrants are likely to experience higher taxes in rich countries than they did in their countries of origin. Second, South-South migration is usually less expensive than South-North migration, because distances are shorter (as a large majority of South-South migration is to nearby countries) and air travel is less necessary.

The impact of the migration shock on natives and existing migrants is smaller for South-South migration than for South-North migration. Natives in developing countries see no significant change in wages from greater South-South migration, while existing migrants experience a decline of more than 6 percent. In the South-North migration simulation, natives see a decline of 0.7 percent in wages and existing migrants a decline of 13 percent.

Obviously, this exercise is subject to many qualifications. In addition to weak data, a significant share of South-South migration is unrelated to income differences between countries.

Also, the simulations cannot account for many issues that affect the wage gains from migration, such as the legal status of migrants. Moreover, an analysis would have to consider broader issues (e.g., the costs and benefits of diversity, the costs of separation from family and friends, and the risks of exploitation and abuse).

Irregular migration. Irregular migration is difficult to measure, particularly in developing countries. Some observers claim it is more common in South-South than in South-North migration flows. It is likely that a higher proportion of South-South than South-North migration occurs without valid documents.

Several factors, related to some degree to combinations of strict (or unclear) rules against legal immigration and weak enforcement, conspire to make irregular migration common in developing countries.

Irregular migration can leave individuals open to exploitation (see the section on trafficking, below) and abuse by authorities. The high rate of irregularity in South-South migration, coupled with weaker law enforcement in the South than in the North, implies that South-South migrants may face greater risks than South-North migrants.

Irregular migrants can also be more vulnerable to being robbed in transit, with or without the collusion of authorities. The police and courts are considered ineffectual in stopping theft on the border between Lesotho and South Africa, and the Inter-American Commission on Human Rights reports that corrupt officials in Guatemala and Mexico collaborate with smugglers and traffickers in the abuse of migrants.

Health. Although particularly vulnerable to and capable of spreading disease through their travels, migrants lack access to medical assistance. In Africa, the largely temporary nature of migration, with migrants returning home to their families on a regular basis, provides a corridor for infection. Regions with higher seasonal and long-term mobility have higher rates of HIV infection, particularly along transport routes and in border regions.

Migrants also may be more vulnerable to acquiring infections due to opportunities for sex with multiple partners, including with commercial sex workers. Detailed studies of African migration find that the likelihood of HIV infection rises with migration and with the concentration of migrants in destination countries.

Evidence of disease transmission through migration is increasing in Asia. A few sending countries (notably the Philippines) require HIV tests of departing, and occasionally returning, migrants.

While the spread of disease through migration is common to North and South, the consequences can be greater in the destination countries of the South because of the more generalized lack of access to health care services. Few developing countries have incorporated migrant health issues into their public-health policies and AIDS planning.

Gender. Globally, the number of female migrants is estimated to have increased from 35.3 million (or 46.8 percent) in 1960 to 94.5 million (or 49.6 percent) in 2005.

The share of women among migrants in developing countries was about 38.9 million (or 51 percent) in 2005, compared to 46.2 million (or 51 percent) in the high-income countries belonging to the Organization for Economic Cooperation and Development (OECD) and 8.7 million (or 40 percent) in the high-income, non-OECD countries.

The share of women in South-South migration varies considerably by migration corridor. In some countries, the increase in female migrants reflects changes in labor demands. For example, the entry of women into the workforce in some middle-income countries has created a growing need for domestic workers.

Difficult economic conditions in other developing countries have led to a greater participation of women in the informal economy— as cross-border traders or street vendors, for example. Moldovan women migrate to Turkey and the Russian Federation to market produce and work as small-scale produce vendors.

However, a number of developing countries (e.g., Afghanistan, Algeria, Bangladesh, Democratic Republic of the Congo, Gabon, Libya, Pakistan, Sudan, Uganda, and Swaziland) have policies to discourage or forbid women from emigrating. In other countries, changes in the sectoral composition of labor demand have affected the share of female migration.

The growing importance of domestic workers in migration underlines concerns about exploitation. In some countries in Asia, for example, the entry, stay, and work of migrants are linked to a specific employer, thus limiting migrants' ability to change employment and increasing their vulnerability.

Migrant vulnerability to HIV and other infections can, in some cases, affect women more than men. The International AIDS Conference in Bangkok in 2004 identified a particular prevalence of HIV among female migrant workers in Asia.

Trafficking in persons. Estimates of the number of people trafficked across international borders vary widely and are subject to considerable uncertainty. Victim surveys show that most trafficking originates in developing regions but plays itself out in low- and high-income countries alike.

In sub-Saharan Africa, where irregular migration is probably the dominant form of migration, children are trafficked for farm labor and domestic work, and women and young persons for sexual exploitation. UNICEF estimates that up to 200,000 children are trafficked annually in West and Central Africa, while, in East Africa, women are abducted from conflict areas to work in the sex trade.

Developing countries also serve as important transit points for conveying trafficked migrants to industrial countries. For example, Albania is an important link in trafficking networks that force women to work in the sex industries of Western Europe. India serves as a major destination country for women trafficked in South Asia; from India many are transited to countries in the Middle East.

The frequency of trafficking in South-South versus South-North migration is unclear. On the one hand, weaker law enforcement, and perhaps a greater frequency of irregular migration, may make trafficking more common in developing countries. On the other hand, higher returns in industrial countries may increase the supply of trafficked women and children there.

The United Nations, in its "World Economic and Social Survey 2004," found that individuals are generally trafficked from developing to industrial countries, or toward neighboring countries with marginally higher standards of living.

Instability. While not captured in the stock data presented earlier, migration flows among developing countries may tend to be less stable than flows from developing to industrial countries for three reasons.

First and most important, South-South migration flows are unstable because of the high incidence of conflict in many parts of the developing world. Net migration rates are extremely unstable in Africa due to conflict, and several countries have alternated between being net receivers of immigrants and net senders of emigrants over the past 30 years.

Second, migrants have been subject to mass expulsions or other pressures to leave, often in response to economic downturns. Expulsions of nonnationals have occurred in many African countries, three times in Cote d'Ivoire alone. Other examples include ethnic Chinese leaving Vietnam en masse at the end of the 1970s, Tunisians and Egyptians leaving Libya during the 1980s, and Haitian sugar workers leaving the Dominican Republic in the 1990s.

Third, economic cycles may affect South-South migration more than South-North migration. Developing countries experience more extreme economic cycles, on average, than do industrial countries.

Also, the incentive to migrate is subject to threshold effects. That is, below a certain level, income differences are no longer adequate to encourage migration.

Instability due to conflict and expulsions can have high costs for migrants and can represent a financial and security concern for countries hosting refugees. Sudden inflows of return migrants may also impose significant costs on origin countries.

For example, the Gulf War of 1990-1991 led to a return inflow to Jordan equal to 9 to 10 percent of the population. This return of Jordanian citizens (mainly Palestinians) from Iraq boosted unemployment, increased demands on social services, and added to the shortfall in water supply. Poverty levels rose, because many of the returnees were poor, remittances declined, and former remittance recipients now had to support returned family members.

Nevertheless, the return generated some long-term benefits owing to the arrival of large numbers of professional and skilled workers. Some returnees brought with them substantial financial resources, which contributed to an economic boom toward the end of 1992.

Unstable migration flows that result from economic cycles have welfare implications that are unclear. Migrants who find their expectations of higher incomes disappointed because of a sudden change in the economic climate are, of course, harmed. But workers — those who choose not to migrate because employment prospects in their home country have risen relative to neighboring countries — gain.


The available data and literature indicate that migrants who travel to other developing countries enjoy much lower increases in income, are more likely to be irregular, are subject to greater risks of exploitation, and are more likely to be expelled than are those who migrate from developing countries to industrial countries.

Nevertheless, if the benefits from South-South migration are limited, it is also likely that many South-South migrants are poor, or are forced to migrate because of war or ecological disaster. Even small increases in income can have very substantial welfare implications for people in such circumstances.

The magnitude of South-South migration suggests that policymakers need to attend to the issues it raises. Developing-country governments have made efforts to improve the management of South-South migration through bilateral and multilateral treaties, and through participation in multilateral processes.

But, overall, the policy challenges that South-South migration presents — high remittance fees, irregular migration, the spread of contagious diseases, among others — remain underappreciated.

This two-part series is based on World Bank Working Paper No. 102, "South-South Migration and Remittances." For the full paper (in PDF format), click here.