Nobody paid much attention when a large white van with Arizona numberplates pulled into a parking space in the shade of the 15ft-high sheet-metal wall that separates Mexico from the United States in the divided border town of Nogales.
A few yards away US border guards monitored the steady flow of pedestrians through a heavily fortified gate in the wall. There was no reason to be suspicious of a van legally parked on a metered space directly beneath a pylon of American surveillance cameras.
Yet inside the van Mexican gangsters were preparing one of the most brazen smuggling ploys ever recorded along this notoriously leaky stretch of Arizona’s border with Mexico. The back of the van had a hole in its floor. The gangsters had acetylene blowtorches and tools to dig a hole in the street.
Using passing traffic to conceal the noise of their digging, the Mexicans broke the surface of the road beneath them and connected with a tunnel that their co-conspirators had dug under the border wall from a house close by on the Mexican side.
For at least two weeks, according to US federal agents, Mexicans crawled down the tunnel to pass drugs into the van. Illegal immigrants may have followed. Each time the van filled up, the entrance to the tunnel was covered with a metal plate and resealed with a thin layer of tar, easily removed the next time the van returned.
It took a tip from a paid informant to alert the US authorities to the smuggling under their noses. All that is left of the tunnel on the US side today is a tar smudge covering the hole, which the Americans filled with cement.
Mexico’s drug and people smugglers have long been renowned for the creativity of their cross-border ruses. Border agents still talk about Enrique Aguilar Canchola, who was found a few years ago disguised as a car seat—he had been covered in a seated position with stuffing and material that made him almost unrecognisable.
Yet despite the four-pronged efforts of US border, customs, drug and immigration agencies, low-tech cunning continues to haunt America’s increasingly expensive efforts to stem the tide of illegal traffic across the Mexican border.
Of the 1m arrests of immigrants—known locally as “wets” or “wetbacks”—by the US border patrol last year, more than 600,000 were made in the rugged desert of Arizona. Nobody can tell how many passed through tunnels or how many escaped undetected, but American agents are under increasing pressure to find new ways of detecting movement underground.
“There are so many tunnels under Nogales, we’re just waiting for the whole place to cave in,” said special agent George Gibson as he drove me around town pointing out houses, sheds, manhole covers and even a former church that had been used to conceal tunnel exits.
Mexican tunnellers are known to have been active along the border for years, but the issue has acquired a new urgency in Washington after the discovery in January of a half-mile-long tunnel built 80ft under the border fence at Otay Mesa, 15 miles southeast of San Diego.
Both the Mexican and American entrances to the tunnel were concealed in vacant warehouses on either sides of the border. It was tall enough for a man to walk through and was equipped with lighting cables and water pumps.
The tunnel must have taken a year to build and cost up to $1m. More than a ton of marijuana was seized when the US warehouse was raided in January. It may also have enabled thousands of immigrants to pour into America without being detected.
Fears that the tunnelling traffic might also include terrorists prompted a group of US senators to propose new legislation this month imposing stiff penalties on tunnellers. Legislators continue to argue over whether a wall should be built along 700 miles of the 2,000-mile border.
Despite budget cutbacks elsewhere, President George W Bush has proposed a $3 billion increase for border security. Millions of dollars are being lavished on high-tech sensors and surveillance cameras, and the Arizona National Guard is about to take delivery of a dozen Predator surveillance drones similar to those used in Iraq.
Yet none of this seems to be able to stop the desperate hordes of would-be immigrants and the so-called “coyotes” who guide them across the border. “We see the strategies change, but the actual problem itself is a constant one,” said senior agent Kent Johansson at the Tucson Homeland Security office.
Other agents snort with derision at the political posturing in Washington. “Politicians need to look as though they are doing something to keep voters happy,” said one veteran who has worked the border for 15 years. “But people up there need to come down here and see what we’re facing. This situation is not under control.”
Most of the tunnels found in Nogales connect with an underground storm-water drainage system that was built decades ago to protect both sides of the border from the severe flash flooding that afflicts desert towns.
One of the sluice channels runs directly under the main border crossing in the centre of town. “We’ve seen people walking directly underneath us,” said Gibson as we peered through a grate surrounded by border agents checking Mexican cars.
US agents went into the drains to install iron grilles to block the immigrant flow. The coyotes responded by cutting through the bars with blowtorches. “Every now and then you can smell the marijuana passing below,” said officer Brian Levin of US Customs.
For the hapless immigrant who has paid between $500 and $2,500 to be guided through a tunnel, the experience is hardly a pleasant one. Some of the smuggling routes go down sewer pipes crawling with rats.
The coyotes dig smaller tunnels out of the drainage system into nearby buildings. “These are not sophisticated tunnels like they found near San Diego,” said special agent Bob Devine. “You have to be slim and agile and crawl on your belly to get through them.”
Some of them are used mainly for passing drugs on a makeshift pulley system that hauls packages under the border.
Last week some of Gibson’s men joined a multi-agency team that had been tipped off to a new tunnel leading out of the drains. Agents first sent a robot fitted with a camera along the tunnel to see where it ended. The robot got stuck and a man was sent in to explore.
Clad in a special hazmat (hazardous materials) suit he wriggled to the end of the chokingly filthy passage. It turned out to be an unfinished tunnel that stopped at the edge of a road. The agents filled it with cement, but Gibson was sanguine about the deterrent effect.
“We are just making them work harder, that’s all,” he said. “As fast as we cover them up they dig new ones.”