The wheels that smuggle migrants from Central America into the United States illegally are being greased by lax prosecution, high-level corruption and the big profits to be made by criminal networks in Mexico.
The death of 10 migrants found in the trailer of a truck in the sweltering summer heat of San Antonio in Texas last weekend has thrown the persistence of the human- trafficking problem into sharp relief.
"This happens more often than we care to imagine," Mr Jonathan Ryan, executive director of Raices in San Antonio, which provides legal services to immigrants, told USA Today. "We see it day in and day out in our offices."
According to US Customs and Border Protection, agents in the Laredo area of Texas found 111 illegal migrants between July 4 and July 8 alone, many of them locked in big trucks, or lost in open country after being abandoned by smugglers. They were from Mexico, Ecuador, Guatemala and the Dominican Republic. In several cases, the drivers of the vehicles were arrested.
Criminal organisations "view these individuals as mere commodities", Laredo Sector Assistant Chief Patrol Agent Gabriel Acosta said on the agency's website.
The problem is complex. It begins with chronic poverty and violence in politically volatile and corrupt Central American countries. People looking to escape that have turned to increasingly sophisticated criminal groups - referred to as coyotes - to smuggle them, and often their entire families, to the US through a complex logistical chain.
Organised criminal groups involved in smuggling migrants across the border between Mexico and the US appear to be based largely in Mexico and Central America, the United Nations Office on Drugs and Crime (UNODC) said.
"For the smugglers, there appears to be little risk of arrest, as they normally pretend to be irregular migrants themselves and are repatriated rather than apprehended," noted UNODC on its website.
Around three million people from Mexico and Central America enter the US illegally each year, generating an annual income of about US$6.6 billion (S$8.9 billion) for criminals, saidUNODC.
Money lubricates the route. For example, criminal groups in Mexico that control territories along the border charge fees to people-smuggling networks, said Dr Guadalupe Correa-Cabrera, a fellow at the Wilson Centre specialising in trafficking in persons, irregular immigration and transnational organised crime in Central America and Mexico.
Border security has been tightened on both the US and Mexican sides since a wave of migrants from Central America came northwards in 2014. Mexico has also tightened security and stepped up deportations on its southern border.
Yet, prosecution is the big problem, said Dr Correa-Cabrera. "There is good coordination between the US and Mexico on the border. But there is a high level of corruption, including at the government level (in Mexico)," she told The Straits Times. "It is mostly low-level smugglers who are prosecuted. They have been unable to dismantle the criminal networks."
Experts say countries across the region have failed to adequately coordinate a response to the issue.
Ms Martha Sanchez Soler, coordinator of the Mexico-based Mesoamerican Migrant Movement, told Inter Press Service last month: "Agreements that exist between countries are aimed at cracking down on people to keep them from crossing borders. But there is not one bilateral or trilateral agreement that really seeks to solve the problem in an integral manner."
Dr Correa-Cabrera said that because border security has been tightened and the US Border Patrol operates within 161km of the US border, the logistics chain must extend into the US, which renders operations more complex and therefore more expensive.
For someone desperate enough to leave poverty and violence in Guatemala or El Salvador or Honduras, it can cost up to US$8,000 for the services of smugglers to get to the US. Families go into debt to raise the money.
Sister Norma Pimentel, executive director of Catholic Charities of the Rio Grande Valley (CCRGV) in Texas, told The Straits Times: "The smugglers used to charge US$4,000 last year. That has almost doubled."
The CCRGV runs a "respite centre" in McAllen, Texas, which sees a steady stream of 10 to 25 migrants, many of them women and children, visiting every day for shelter and guidance.
Most had used the services of human smugglers, she said.
