Milson, from Honduras, sits with his 14-year-old daughter, Loany, on the reedy riverbank beside the bridge connecting Matamoros, in the Mexican state of Tamaulipas, with downtown Brownsville, Texas, across the Rio Grande.

On the far reach a few yards but another world away is a vast tent (officially a soft-sided facility) erected to cope with the sheer numbers seeking asylum in the US. In a few weeks time, on the date stipulated on their notice to appear document, the people staying here will have their credible fear interview by video link.

On the Mexican side, clinging to the bridge like barnacles, are hundreds of smaller tents, where roughly 1,000 people are gathered for safety, in fear of the mafia that has kidnapped, murdered or disappeared hundreds of migrants over the past decade. It is a tent city where, says Milson, time passes very, very slowly. Almost all are from Central America.

Upriver at Ciudad Acua, about 250 people are encamped in the ecological park, staring across at the lights of Del Rio, Texas. Most are from Cameroon, Angola or the Democratic Republic of the Congo.

Further west, at Ciudad Jurez, a mix of Cubans, Central Americans, a Ugandan and an Indian kill the endless time in the yard of a Methodist-run shelter. On the borders far western edge, in Tijuana, Haitians trade on the streets a community of hundreds who came to cross, but remained in Mexico.

Ten years ago, most people trying to cross into the US from these various places were Mexicans, in flight from poverty or violence.More recently, though, there had been a lull, with Mexicans nowhere to be seen at some crossing points. But 2019 figures show a renewed rise in Mexican asylum seekers, as the narcotraffic cycle of violence returns to record levels. Roughly half the asylum-seekers on the border are now Mexican.

As the migration crisis on the US-Mexican border becomes a full-blown humanitarian catastrophe and the centrepiece of Donald Trumps re-election campaign, one thing is clear to those who have supported migrants over decades: the world has converged here. Such are the historical and geopolitical layers of migration to the busiest border in the world, gateway to the globally ubiquitous American dream a dream now twisting into a nightmare.

Woody Guthrie wrote his song Deportee about migrants working and dying in Americas deserts in 1948. It remains resonant, but the cast has changed.

Mass migrations began with poor Mexicans crossing to work in Americas farms, and continued with the bracero programme a Spanish term for a labourer initiated in 1942, which gave limited access to American jobs. The scheme ended in 1964, yet vast numbers of Mexicans continued to cross, legally and illegally.

During the 80s, when civil wars erupted across Central America, tens of thousands tried to cross, many finding a place in the US thanks to the sanctuary movement, which gave a path to legality.

All the while millions of Mexicans came to the border not to cross but to live on it, in maquiladora assembly plants, producing goods exported duty-free to the US.

From 2006, as the cartel wars devoured Mexico, more fled, seeking safety in the north. The demographics changed again.

Methodist pastor Juan Fierro Garca, who runs the shelter in Jurez, says: More people than ever are on the move from generalised violence all over the world, seeking safe places for themselves and their children. And if anyone thinks this is going to stop, think again this is just the beginning.

The Trump administration has met this surge in arrivals with a policy of deterrence based on fear and brutality.

The separation of children from their parents for incarceration outraged the world. The policy was ruled illegal by US courts and abandoned, though hundreds of children remain separated after their parents were deported. Internal documentation leaked from US Customs and Border Protection shows full knowledge of the traumatic affects of child separation. Unaccompanied minors crossing the border continue to be detained in appalling conditions. In December, ProPublica published CCTV footage that appears to show a Guatemalan teenager left to die in a concrete cell.

An internal report from last July, seen by the Guardian and written by Jennifer Costello, the inspector general of homeland security, to acting director Kevin McAleenan, warned that at-risk populations are subject to overcrowding and prolonged detention. But Trump intends to expand the number of those detained rather than deported under migrant protection protocols (MPP).

Under MPP, non-Mexicans from Spanish-speaking countries cannot remain in the US to await their credible fear interview, as is mandated under the 1939 Montevideo treaty on asylum. They must instead wait on the Mexican side, with the result that 57,000 asylum seekers, mostly from Central America, are now encamped south of the border in unsanitary conditions, prey to kidnap and extortion.

Under another policy, called metering, daily asylum applications are limited, so that unofficial waiting lists, thousands-long, are drawn up on the other side. The Trump administration announced in January that it plans to extend the MPP to Portuguese-speaking Brazilian asylum seekers.

The policies are working: US Customs and Border Protection report that the number of arrests for illegal crossings fell 75% from May to November last year, from 132,000 to 33,510. The reason is simple: word reaching the Mexican side of how appalling conditions are.

The chapel at the Methodist Buen Pastor shelter in Jurez has become a dormitory for young mothers and children, among them Marisela del Carmen Espinosa, who lays her seven-year-old son, Diego, on a blanket; the child is running a fever. Marisela fled El Salvador when the MS-13 gang demanded she join them the problem being that Diegos father was among them.

They came to my house, armed, saying they needed me to do tasks for them, and if I didnt theyd kill me and the boy, she says. Marisela has spent the past year on trucks and railway cars, crossing Mexico, paying $8,000 (6,211) to coyotes and other people smugglers. To her horror, Diegos father has traced her to Jurez, and Im scared when I go out for food, because he said his contacts here would take our son and kill me. I know that the police and gangs are friends if I go to them for help, Ill be killed.

In the mens dorm, Evian Mvouba, from DRC, prepares to cross and make his asylum claim. He stands a better chance than his Central American companions since MPP does not apply to Africans. But he does fall under the metering system, and more than 2,000 people are ahead of him on the list.

Evians village was attacked by government forces 18 months ago. He has since journeyed through Angola, Brazil, Colombia and Central America, with no word of many of his family members. It is limbo, he says, not knowing where I live, and whether they are alive. Most of my fellow Africans have moved on, and a few have been successful because they are politically persecuted more than the people here from Guatemala and Honduras.

In all these shelters the Cubans look different better clad and fed, escaping not violence or desperation, but a regime they fear or despise.

Pedro Ruz Tamayo is an opposition leader, educated and erudite. Youll not find a Cuban in Jurez who supports the regime, he says, but youll not find many who contest it. They just want to try their luck in the US.

Pedro commutes between the shelter and an emerging Little Havana in Jurez, consisting of people waiting to cross or refused asylum and returned.

Ariel Busquet kneads burritos in the Llenadora caf. He was number 13,527 on the waiting list to cross. After hearing from a friend who returned following three months incarceration on the other side, he elected to remain in Jurez. We Cubans left our country to work for a wage something we cannot do there, he says. But thats what Im doing here in Jurez! My relatives call themselves Cuban-Americans; I call myself a Cuban-Mexican.

In El Paso, Ruben Garca has seen each migration wave arrive since 1978, when he first opened Annunciation House, which is now a network of shelters for migrants. The shelters have been vital to current efforts to abate the suffering.

Without radical Catholicism of the kind that inspires Garca, far less would happen on the migrants behalf. To overlook the faith of those who do this is to not accurately report what is happening.

Forty years ago, a group of us started this work, he says. We made a decision to offer hospitality to undocumented migrants.

But we also talked to reporters, universities, hoping we could bring about change for the better. And 40 years later, we have Mr Trump as president and below him very capable officials whose sole task is to make life unbearable for refugees. It makes me think of Lazarus, restored to life by Jesus, who turned to the community and said: Unbind him. In this situation, it is the refugees who unbind us, sharing their stories, their struggles. Thereve been days when weve received hundreds of people.

One night, up to 1,000 migrants were released on to the streets around El Paso bus station. TV coverage showed Garca, arms wide, saying to a group: Bienvenidos! welcome and it seemed the first kind gesture they had encountered in months.

Garca has seen generations of migrants flee death squads in the 1980s, when war was war, and you knew who the sides were, to this new kind of undeclared war, where no one knows the rules, and you live in a state of permanent insecurity. Plus drought and crop failure.

You either give up your children to those realities back there, or you pay the coyote, subjecting yourself to debt bondage and whatever risk, and leave.

Migrants need guidance through a system designed to fail, says Molly Molloy, up the road in Las Cruces. Molloy worked as an archivist at New Mexico State University, but has retired to work with migrants, something she first did in the 80s. She is now a paralegal, translator and researcher for immigration lawyer Nancy Oretskin.

In the civil wars in the 1980s migrants were mainly people who had never been to school or left their hamlet and, with successive waves of migrants, blocks have been laid in response, says Molloy. September 11 2001 was a dividing line, after large numbers, mainly Mexican men, fled poverty as the result of the North American Free Trade Agreement and clearance of subsistence farms. Then came two further push factors: Mexicans fleeing violence after 2006, and the great recession, after which there were just fewer jobs for these people.

And now climate change, and in Central America, violence of gangs that were initially deported from Los Angeles. A level of violence more extreme, on a daily, monthly basis more people killed even than during the civil wars.

Oretskins family were migrants. I was raised by crazy Jewish entrepreneurs raised to think: dont you ever forget.

Handling 10-15 asylum cases a year, she works in the immigration courts where 90% lose, affording a second bite at the cherry to the Board of Immigration Appeals, where 99.9% of the 90% lose.

The evidence required by an applicant is often impossible to produce, says Oretskin. If you dont have a doctors report, it did not happen. If you are attacked in El Salvador, the gang will say: Go to the doctor and well kill you. We have reports of doctors in cahoots with gangs.

Occasional successes are usually among Africans. Oretskin shows a wedding photo of one client, from Cameroon, permitted to stay after being kept in a gym in Ciudad Jurez for three weeks, and staying at my house when she had nowhere else to go.

What sets Trump apart, even in an environment systematically stacked against refugees, is the brutality of the manner in which rules applied. Former secretaries of homeland security, she says, had some idea of what cannot be done because it is illegal. But the people there now are there just because someone has to be. We do not even have due process, let alone justice.

Night is eerie in the ecological park at Ciudad Acua, where the Rio Grande is shallow enough to wade to Texas. Many do it to surrender to the Border Patrol and apply for asylum, but as metering limits the numbers and the wait lengthens, so the temptation rises to slip across illegally.

Charly and Loreley, a father and daughter from Cameroon, have travelled on foot, by ship and bus, via Nigeria, Brazil, Ecuador and Central America, paying $6,000 to smugglers.

Charly, a schoolteacher, says his community was continually harassed by militias of the French-speaking government, until one raid last year incinerated dozens of houses, and he was arrested, detained and tortured.

This cannot be the end of our long road: lavatories that leak into the ground, rubbish piling up that no one collects, he reflects.

Not all migrants want to cross. Some are stung by experiences on the other side, others just tired of waiting.

On the borders far western edge, Tijuana has become home to thousands of people who once intended to cross, but have remained.

Robenson Metellus is among the hundreds who arrived from Haiti after the 2010 earthquake, having travelled through Belize, Guatemala and Mexico only to be refused asylum in the US. Rather than return, he proceeded from the Casa del Migrante shelter to selling souvenirs to tourists.

After a year, Robenson got a job in a coffee house and by night started a food delivery service Mexican and soul food. He is now arranging for a sister and son to join him from Port-au-Prince.

Robenson is part of a singularly successful assimilation, says the citys prosecutor, Jos Alberto lvarez: Theyve been largely welcome; people find them interesting, and admire their work ethic. Do you know how many Haitians Ive indicted on a serious felony since they arrived? Zero.

At the Zacazonapan bar in the red light district of Tijuana, thick with marijuana smoke and packed with Tijuaneros plus gringos in town for cheap drink, a Norteo band is playing. Resistencia Migrante was formed in the Espacio Migrante shelter. On keyboard is Olivr, who spent two years travelling from El Salvador and seven months in Tijuana. He has given up trying to cross the border; his flight from gang threats was insufficient for entry to the US, so he tried to cross illegally but was caught. Weve abandoned the American dream as a nightmare, he says, and its OK here. We are survivors.

In Tijuana, lawyers and volunteers are mostly concerned with what Nicole Ramos, at the Al Otro Lado migrant resource centre, calls trying to get the US authorities to abide by their own laws, which they dont. Though, she adds, terrifying numbers of our people just disappear in this city.

The Mexican state is nowhere to be seen in all this. Grupo Beta, an organisation formed by the Mexican government to help migrants, has been withdrawn from some areas after allegedly taking bribes to move people up the waiting list. Almost all in Matamoros are from Central America, awaiting their credible fear interview on the other side. Conditions here are so bad that migrants blocked the bridge to Brownsville in protest in October.

Milson and Loany sit by the river. Lack of fresh water makes them tempted to wash, with others, among the same eddies and whirlpools that drowned another father and daughter recently as they tried to swim to the far bank. Milson and Loany come from Tegucigalpa. This is Milsons third attempt to cross, and we joke about a hit song by Los Tigres del Norte, Tres Veces Mojado three times wet (from swimming the Rio Grande).

Milson made it in 2014, but was deported. Before his second attempt, he was kidnapped by a gang, Los Zetas, and held in the desert for eight days. He is coy about how he was released, suggesting payment by a cousin in St Louis. They told me that if I ever came back, theyd kill me, he adds. He crossed, was again deported, and returned to Honduras for good, he thought. But then the MS-13 informed me: Were having your daughter. I said: Come on my love, were leaving.

Father and daughter were separated for a week on the US side. They kept us in the heat by day, and as cold as the air-conditioning would go by night, with filthy blankets and toilets, says Loany. When we asked them to turn the cold air off, they refused.

Milson is clear. I know some of the parents whose children have left [to go to the US alone]. Theyre devastated, whether they knew or not. Id never let Loany go without me thats why we are here, so she can be safe with me. It has to be legal, and together or not at all.

Loany concurs: Im staying with my Papa.

The conviviality in such extreme hardship is remarkable; there is almost no friction. They line up for breakfast in respect of priority for women and children, served by a group called Team Brownsville from across the river, founded by Michael Benavides, a former bomb disposal soldier, now Mormon missionary.

People disappear. Its so scary, he warns. Youll agree to meet someone next day, come back, ask around, and no one knows where they are. They cannot do everything to defend against the mafia, but they look after each other. Watch them, he says, as volunteers hand out plates of beans, not a push or shove.

Benavides has the names of two teenagers who died in US government custody on two crosses, tattooed above his heart.

Team Brownsville started out cooking in a tiny kitchen a block from the border, then expanded raising money and buying tents, driven by a belief, explains Benavides: that this is what America should be. My grandparents came from Mexico, and raised me to think of America as a country of compassion and open arms to those in need. This is my idea of patriotism. The operation feeds more than 600 people, we just need to keep raising the funds to keep it going, he says.

Lining up for breakfast are Jocelyne Flores and her daughter, Imena, four, sent back under migrant protection protocols. Pregnant Jocelyne left San Salvador after Imenas father who beat her - threatened to kill them both. It has been explained to her that domestic violence is no longer grounds for asylum, but Jocelyne is confident theyll make an exception. Glady Caas Aguilar takes her under her wing and makes an arrangement with the local hospital.

Glady runs the list of those waiting to cross. La lista, la lista! - how I hate it, she says, as they call out names of those due to cross at 4am.

Fork lightning and rain break over the camp. Night falls, and a group sits among the puddles, as torrential water lashes the concrete, singing they all know the lyrics a hit by Tropa Vallenata, called The Roads of Life:

Los caminos de la vida / No son como yo pensabaComo los imaginaba / No son como yo crea

(The roads of the life / Theyre not as I thought / Not as I imagined them / Not as I believed)

Read more:

How the American dream died on the world's busiest border - The Guardian