Book of the Week: A Line Becomes a Wall tells the story behind Donald Trump's border rhetoric

Cantú saw the Patrol as a stepping-stone to diplomatic service or a job as an immigration lawyer, and as a Spanish speaker and trained paramedic, he thought he’d be able “to become a force for good in the agency”. But the parade of casual brutality, misery and desperation took its toll: he suffered horrific nightmares and ground the enamel off his molars.

After quitting in 2012 he took a job in a coffee shop, embarked on a period of self-examination and research, and almost by accident found himself involved in the tragic case of a Mexican work friend, Jose, who faced deportation after 30 years. All of which ultimately fed into his book.

The Line Becomes a River, Radio 4’s Book of the Week, is brilliantly evocative of the starkly beautiful reaches of the desert and of the human stories behind the statistics. Cantú brings to life the immigrants he briefly meets, and does not demonise his former friends and colleagues on the Border Patrol, even as he records them shredding clothes and urinating on foodstuffs cached by desperate individuals in the desert.

Alongside the personal dimension, Cantú intelligently explores the history and causes of Mexican immigration to America, and the US response.

“Our government policy, ‘prevention through deterrence’, means cities are well enforced, so crossers are pushed to more remote desert areas,” Cantú says. “Hundreds of people are dying in the desert each year. Our policy has precipitated a humanitarian crisis.”

It has also unintentionally professionalised the smuggling gangs. At least 6,000 people are known to have died on the US/Mexico border this century, Cantú says. And what is happening there is replicated in the Mediterranean, in the Middle East, in Africa… “These deaths are not acknowledged, not mourned, to the extent I think they should be,” he says. “Those statistics are made up of individual lives. This is what I am most eager to change: to personalise the conversation for people.”

He is not a fan of Trumpian rhetoric, but he understands it. “People are thirsty for easy solutions, so ‘build a wall’ sounds great,” he says. “And ‘open borders’ is the other extreme that makes sense to us, but what I hope to do with the book is present the border as something deeply complex and nuanced.”

He adds that some 700 miles of the 2,000-mile boundary are fortified, and that smugglers jack up the panels and drive vehicles underneath, or cut human-sized holes in them with blowtorches: “No matter what obstacle we put up, people will always find ways up, over or around it.”

Cantú grew up in Prescott, Arizona, with his mother, a park ranger, and had little sense of his Hispanic identity until he travelled through Mexico as part of his studies in immigration and international relations at the American University in Washington DC.

After graduating, he thought a job at the Border Patrol would give him real-life experience of everything he’d read. “I was a literary nerd in college,” he says, “but I saw literature as an afterthought, until it became something I had to do.”

His first drafts were direct transcriptions of journal entries, hence the book’s terse style.

“A lot of writing about the desert is sparse,” he says. Much of his wider reading came from his attempts to make sense of what he’d been part of. In the book, he says that most of his life was spent circling the foot of a giant, before looking up and “finally seeing the thing that crushes”.

Today, Cantú lives in Tucson, Arizona, and translates other writers’ work from Spanish to English, while formulating his own next writing project. “None of my ideas is fully formed enough to embark on yet,” he says, “but I want to continue to look at our border, and at borders more broadly. I think these issues that we see play out on the border are a microcosm of other issues. And I want to continue plumbing those depths.”

Book of the Week: The Line Becomes a River Monday–Friday 9.45am Radio 4 FM