The US-Mexico border: where the drugs war has soaked the ground blood red

Cartels have murdered thousands in the past four years as they fight over the spoils of hugely lucrative trafficking. American policy has only fuelled the carnage. The chaos will not change without fresh thinking

The border between Mexico and the United States is chaotically reverting to historical type, the place of horror it was for most of the 19th and 20th centuries. Nearly 19,000 people in Mexico have been slaughtered in drug violence since 2006, the year the conservative Felipe Calderon was elected president and began deploying some 50,000 troops and federal police in support of the US-convened struggle against street drugs. The line between the two countries – marked on the US side with the remains of what was to have been an electronic version of the Berlin Wall – is once again the world's most lawless and blood-soaked frontier.

Four decades ago President Richard Nixon proclaimed that the US was launching a "war on drugs" and started a strategy to fight on foreign – and particularly Latin American – territory the battles against his compatriots' use of narcotics at home. Today, despite the efforts of the White House to pretend the war is a thing of the past, hostilities with all their incalculable profits, extreme violence, double-dyed treachery and political confusion are blowing back on to US territory. The toll in dead, injured and refugees is climbing swiftly to Colombian or even Iraqi levels.

Gangs are using increasingly indiscriminate violence to intimidate their rivals, the security forces and innocents alike. A US couple were killed in crossfire between gangs while returning from a party in Ciudad Juarez, while their six-month-old daughter cowered on the back seat. A 23-year-old woman bystander was cut down in the resort town of Acapulco as feuding cartels settled a score on the streets, killing eight gunmen in the process. A human rights activist, Josefina Reyes, was killed in Ciudad Juarez shortly after celebrating the New Year. And, most gruesome of all, the face of a 36-year-old, Hugo Hernandez, was found stitched on to a football and dumped outside a government building in Sinaloa state, along with a note reading "Happy New Year, because this will be your last". The murder of Hernandez, whose body parts were found scattered around the town, was a warning to members of the Juarez drug cartel, according to state prosecutors.

But the present focus of attention is the border city of Ciudad Juarez where more than 400 have been killed so far this year. (In 2009, the total came to 2,600.) On 31 January, 16 young people were shot dead at a party and last weekend 50 people were killed, including two men and a woman linked to the US consulate-general. The murders prompted a cry of anguish from Barack Obama and the American staff have been allowed to flee north across the frontier to the US city of El Paso.

Juarez used to make a living by providing liquor and sex to gringos, particularly to GIs from Fort Bliss beside El Paso airport. A railway used to meander southwards from its outskirts towards Mexico City, across the cactus-filled Chihuahuan desert; sleeping cars used to ride it with the sort of balconies on the rear from which Mexican and US presidential candidates harangued voters on the original whistle-stop tours. It no longer runs and Juarez is now an armed camp, a battlefield between rival drug cartels.

The north-south line has recently been used by traffickers to move vast quantities of illicit drugs into the US. Last year, the US Department of Justice fined the Union Pacific railroad $37m for failing to prevent the smuggling of 4,200lb of marijuana and 260lb of cocaine from Mexico into Calexico and Brownsville, California, aboard its trains. The operator claims that it is defenceless against gangs hiding drugs behind false floors and in the moving parts of its trains because neither the Mexican nor the US authorities will allow the train company's staff to inspect cars before they become the responsibility of American border police.

The violence in Juarez is such that 16,000 dwellings have been abandoned, more than a quarter of the city's housing stock. It is estimated that up to 400,000 people have left the city. Calderon has just made his third emergency visit there this year. A middle-aged man asked by a TV reporter what he thought about what the head of state had said answered, "Why did he talk about opening new hospitals? We don't need them – 500,000 people have left this city."

Today, Mexico's impatience with President Obama is becoming tetchily evident. "Organised crime has its origin in two phenomena which affect both countries," the Mexican leader said in Juarez on Wednesday. "They are the consumption and the trafficking of drugs in, and towards, the United States; and the trafficking of arms coming from the United States." There is no doubt in Felipe Calderon's mind who are the bad guys.

The outlawing and criminalising of drugs and consequent surge in prices has produced a bonanza for producers everywhere, from Kabul to Bogota, but, at the Mexican border, where an estimated $39,000m in narcotics enter the rich US market every year, a veritable tsunami of cash has been created. The narcotraficantes, or drug dealers, can buy the murder of many, and the loyalty of nearly everyone. They can acquire whatever weapons they need from the free market in firearms north of the border and bring them into Mexico with appropriate payment to any official who holds his hand out.

And drug-related bribery is gnawing deep into US institutions, as Calderon has long alleged. Thomas Frost of the US Department of Homeland Security says that last year the department accused 839 of its own agents of corruption. In evidence to a US Senate committee this month, Kevin Perkins of the division of the FBI charged with fighting corruption within the US government said his – presumably honest – staff had deployed some 120 agents along the border. They dug up more than 400 public corruption cases that resulted in well over 100 arrests and more than 130 state and federal prosecutions.

A multiplicity of US government agencies, some of them deeply infiltrated by narcos with their deep pockets, are falling over themselves in efforts to bring order to a chaotic situation: the Department of Customs and Border Protection, the Transportation Security Administration, the Drug Enforcement Administration, the Bureau of Alcohol, Tobacco, Firearms, and Explosives, and Immigration and Customs Enforcement.

A century ago, President Alvaro Obregon used to say, "There is no [Mexican] general who can withstand a cannonade of 50,000 pesos." Though the US media are reticent in their references, it is clear that the habit of generalised corruption has moved northward. Dr Tony Payan, of the University of Texas in El Paso, said the effect of a heavy charge of dirty money is the same on both sides of the line.

The narcos have penetrated the US embassy in Mexico City (as they had previously the one in Colombia's capital, Bogota), their funds allowing them to siphon out a stream of intelligence about future operations against the narcos.

A dozen people were tortured and murdered between August 2003 and mid-January 2004 in a house in Juarez by a capo in a local drug gang. US officials in the Immigration and Customs Enforcement field office in El Paso were told about the killings but did nothing to stop them since their informant was in a criminal syndicate. The US team wanted to maintain his cover and continue using him to capture others. When a whistleblower alerted the government, he was soundly told off.

Down the Rio Grande, in Matamoros and Reynosa, the drug cartels are taking over the prerogatives of the state. Cars of the local Gulf drug cartel cruise with darkened windows and no number plates, displaying transfers with the letters CDG, standing for Cartel del Golfo. According to the Mexico City daily El Universal, the drivers collect protection money from businessmen and shopkeepers, and fine other drivers for speeding or running through a red light.

On Friday came further evidence of the impunity with which the cartels operate. In Monterrey, one of the country's leading business centres, armed men linked to drug gangs blocked motorways with lorries in an attempt to hamper army operations near the US border. Gunmen pulled truck and bus drivers out of their vehicles in the wealthy business city and used them to set up more than 30 blockades on major four-lane motorways, sometimes slashing tyres to make it harder to tow them away.

The Mexican media and NGOs are critical of Calderon's policy of militarising the northern border. He has used increased dollops of US subsidy to do so, totalling some $1,300m since he became president. One Mexican paper proclaimed this week: "The US puts in the money, Mexico puts in the corpses."