Increasing numbers of people from Asia and Africa are seeking to enter the U.S. illegally over the Mexican border. Analysts have started to map the routes these migrants take, in journeys which are often controlled by criminal groups.

As Mexico’s El Universal reported, in 2010 the country’s National Migration Institute (Instituto Nacional de Migracion – INM) detained almost 70,000 migrants. The vast majority of these, more than 67,000, were from the Americas.

However, a significant number were from Asian and African countries — some 2,300. The biggest source countries in this region were India, China, Nepal, Sri Lanka, Ethiopia, Eritrea and Somalia. Although these intercontinental migration patterns have existed for years, testimony from immigrant rights NGOs suggests that the trend is becoming increasingly common, according to the report.

In a journey that can take years, these individuals use a combination of shipping routes, flights and various methods of ground travel across several continents to reach gateway countries in Central or South America. From there, they make their way to the U.S. through complex networks, called “pipelines,” of human smuggling contacts. Generally, these networks are based in countries where lax border security, lenient immigration policies or easy access to false documents make it easier for migrants to cross the borders.

In Brazil, for instance, travelers from South Africa are not required to obtain entry visas. Because of this, the majority of African migrants heading to the U.S. through Latin America do so by obtaining fake South African passports and traveling to Brazil. As the Miami Herald reported in December 2009, this policy has also helped turn Brazil into the home of the largest population of Africans outside Africa.

For U.S. border officials, some of these human smuggling pipelines are a particular cause for concern. As InSight has reported, Indians are now the second most common ethnic group of immigrants, after Latinos, to be detained at the U.S.-Mexico border. In the whole of 2009, only 99 migrants from India were detained along the southwest border. In the last three months of 2010, the Border Patrol arrested more than 650 in southern Texas alone. Because of the proximity of India to Pakistan, the site of several anti-American armed organizations, the U.S. is concerned that the same smuggling networks could be used to carry out attacks on American soil. Although some fly into South American countries like Colombia and Venezuela, most of the Indian human smuggling networks base their operations in Guatemala, where American officials are pressuring the government to crack down on such activities.

Another country known for its relaxed attitude towards immigration is Ecuador. In 2008 the Ecuadorean government decided to waive visa requirements for foreigners, granting an automatic 90-day stay to all nationalities. As InSight has noted, this approach has made the country a prime midpoint for human trafficking pipelines to the United States. Although President Rafael Correa has since tightened immigration policy due to budgetary strains, his administration continues to facilitate illegal immigration, most recently through the establishment of a program that rewards undocumented migrants with citizenship in exchange for reporting police corruption.

As Ecuador’s case shows, facilitating migration can mean opening the door to criminal groups. The dynamic between the potential migrants and their traffickers can vary widely. Although sometimes the relationship resembles that of a client and service provider, it is often marked by abuse. Often, instead of assisting migrants, human smugglers kidnap them en masse, and have been known to kill one or two from a group as an intimidation tactic, frightening the rest into contacting relatives to meet ransom demands. According to Mexico’s National Human Rights Commission, nearly 10,000 migrants are kidnapped by gangs every year.

Below is a map, produced by El Universal, of the most popular transcontinental migrant routes, along with the major cities that serve as their hubs.

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