A mother and her two young daughters arrived by bus from El Salvador after her husband, a gang member, was jailed for murdering a teenage girl. If you start a life with someone else, she says he warned her when she visited him in prison, I will have you killed.

A Cuban wrestler who joined a sports mission to Venezuela during the era of Hugo Chavez was threatened by the authorities after refusing to pay a bribe. He says he cannot return to either country. Another Cuban exile, who once lived in the US, wonders why Donald Trump noisily claims he is with the Cuban people, but does nothing to help.

Tens of thousands of migrants are presently languishing in scruffy and unsafe towns on the US-Mexico border, gazing at what they believe is the promised land a few hundred yards away. In the latest effort by Mr Trump to try and deter asylum seekers, since January residents of Spanish-speaking countries – having made their applications to the US authorities – are forced to wait for them to be processed, not in the United States, but in Mexican cities, many of which are as dangerous as the places they have left.

While the conditions faced by would-be migrants in US custody, especially by children, have triggered widespread political debate, those endured by applicants outside of the country under the new scheme have received very little attention.

‘Families belong together’ protests over Trump immigration policy Show all 8 1 /8 ‘Families belong together’ protests over Trump immigration policy ‘Families belong together’ protests over Trump immigration policy Mishawaka, Indiana AP ‘Families belong together’ protests over Trump immigration policy Washington DC AFP/Getty Images ‘Families belong together’ protests over Trump immigration policy New York Mayor Bill De Blasio speaks in Tornillo, Texas alongside the many other US mayors who have called for detained immigrant children to be reunited with their families AP ‘Families belong together’ protests over Trump immigration policy Albuquerque Mayor Tim Kelle leaves a teddy bear as a gift for detained immigrant children in Tornillo, Texas AP ‘Families belong together’ protests over Trump immigration policy Seattle Mayor Jenny Durkan and Los Angeles Mayor Eric Garcetti leave sandals as gifts for detained immigrant children in Tornillo, Texas AP ‘Families belong together’ protests over Trump immigration policy San Diego, California EPA ‘Families belong together’ protests over Trump immigration policy US embassy, Mexico City AFP/Getty Images ‘Families belong together’ protests over Trump immigration policy San Diego, California EPA

“The administration calls this new policy the Migrant Protection Protocols (MPPs) but that’s just Orwellian doublespeak,” lawyers for the American Civil Liberties Union (ACLU) wrote earlier this year.

“Indeed, the policy has nothing to do with protecting people and everything to do with making it impossible for migrants to get the humanitarian protection that they are entitled to under domestic and international law.”

The first cities used to trial the new policy, which Mexico agreed to under intense pressure, were Mexicali and Tijuana, which border California. Nuevo Laredo in the northern state of Tamaulipas, which borders Texas, and San Luis Rio Colorado, which borders Arizona, have been added to the list. Reuters said Tamaulipas was home to the Gulf and Zeta cartels, which are involved in people trafficking as well as drug smuggling.

Another border city used as a petri dish for the Trump administration’s so-called “Stay in Mexico” policy is Ciudad Juarez, the sister city of El Paso, Texas, which found itself in the headlines earlier this month after a mass shooting at a Walmart killed 22 people and injured many others. The city, founded when Mexico’s territory spread much further northwards, has a population of 1.5 million, with 700,000 in El Paso. The two cities, separated by the Rio Grande, combine to create the largest bilingual, binational conurbation in the hemisphere.

Thousands of people legally pass back and forth each day, using one of four international crossings, for school, for work, to visit relatives and to go shopping. It is alleged the suspect in the Walmart terror attack intentionally targeted El Paso because of its large Hispanic population. Eight Mexican citizens were among the dead.

“Xenophobic and racist discourse breeds hate crimes,” Mexico’s US ambassador Martha Bárcena, said after the shootings, amid allegations Mr Trump was fuelling violent bigotry with his often racist remarks about immigrants. “Hispanic communities contribute enormously to the American society. We have to work for a respectful and compassionate dialogue between our countries and communities.”

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On a recent morning, The Independent accompanied a group of lawyers and volunteers from El Paso who work free of charge to help some of the migrants stuck in Juarez. The most extraordinary thing about the short walk across the Paso del Norte International Bridge was not any sudden culture shock – indeed, there was little of that – but how quick and seamless the journey was, if you had the “correct” passport or visa.

“The number of people waiting in Juarez is major – it’s eclipsed the numbers in Tijuana,” says Nicolas Palazzo, a staff lawyer with Las Americas Immigrant Advocacy Centre. “One of the problems is that there are only four immigration judges in El Paso to hear all these cases.”

Palazzo explains that MPP policy only applies to Spanish-speaking migrants. The largest number came from Guatemala, Honduras, El Salvador and Cuba. He says a lot of Cuban doctors are in Ciudad Juarez, waiting for the call to assemble at the crossing at 4.30am and cross to El Paso for their hearings. “There has been an increase in Venezuelans,” he says, referring to reports that as many as 4 million have fled since 2015. “But as the crisis has become worse, a lot of countries [such as Brazil, Columbia and Peru] have tightened the situation for Venezuelans.”

The Independent agreed to identify the people the lawyers were speaking to only by an initial and their country, in order to protect them or their family against possible reprisals back home. But close to the borrowed offices in a Mexican municipal building where the lawyers and volunteers worked, there were many migrants expressing anger and frustration, who were happy to provide their full name.

Orlando Alvarez, 54, left Cuba in 1994 and had lived in the US and Paraguay. His green card had expired and he had been waiting four months for his hearing. “It’s crazy here. Juarez is a very crazy city – there is a lot of crime here,” he says.

Migrants frequently try to cross the border to start the asylum process (Getty)

Another Cuban, Rolando Delgodal, left the country recently and has spent three months in Juarez. He said the situation in Cuba had become worse since the death of Fidel Castro and the passing of power to the next generation of Communist Party of Cuba leadership. “We have no free speech there,” says Delgodal, who worked for the government’s department of culture.

John Breslin, an immigration lawyer who lives south of Chicago, was among the volunteers screening potential cases for Las Americas, before a decision was made on whether or not they have a viable claim for asylum.

“I am trying to find out if the facts of their case – the reasons why they left their home country – fit into a valid asylum claim.”

He was working with Octavia Marsh, a former professor of English literature, who grew up in Las Cruces, New Mexico, 40 miles northwest of El Paso.

“People have every kind of story you can imagine. Some have crossed through nine or 10 countries just to get here,” she said. “I hope the US can regularise this process so that these people have a chance to save their lives – literally to save their lives.”

One of their cases was a Cuban, J, who had gone to Venezuela as part of a mission established between the two countries, and married a Venezuelan woman. After being forced to attend political events in support of the Venezuelan government, he quit the mission. Recently he had been threatened by the authorities after refusing to pay a bribe. Having made his way to Juarez, he says he had been robbed at an ATM and had crossed the Rio Grande in order to get detained, in what he hoped would speed his application.

In a windowless office, harshly lit by fluorescent light, he is asked if he could return to Cuba if not Venezuela. “No,” he says. “I would be persecuted for my political opinions and for having deserted.”

The Department of Homeland Security did not immediately respond to questions as to how many people were being dealt with by the MPP process, and claims that migrants were being intentionally forced to wait in dangerous conditions as an intentional deterrent. When the policy was introduced in January, the then DHS secretary Kirstjen Nielsen claimed: “MPP will help restore a safe and orderly immigration process, decrease the number of those taking advantage of the immigration system, and the ability of smugglers and traffickers to prey on vulnerable populations.”

Another case, S, a young woman from El Salvador, is with her daughters, aged two and eight. She says she left her country in May after being threatened by her husband, who she said was a member of the MS-13 gang, and had been jailed for murdering a young woman.

Her daughters are briefly taken outside the room by another volunteer, as S weeps, saying she had been told by her husband if she tried to start a new life without him, he would have her killed and the girls taken away. Did her mother and father want her to leave, she is asked?

“My parents did not want me to go, but I told them I was going,” she says, adding that the police in El Salvador had relationships with gang members. “I am afraid to return to El Salvador.”