It arrives in padded bundles tossed from low-flying airplanes. It comes stashed in the guts of tanker trucks, or packed in rickety sedans driven wildly across the desert. It's carried in backpacks, saddlebags, and even in balloons swallowed by human "mules."
Whatever mode they employ, drug traffickers along the US-Mexico border smuggle about $10 billion worth of narcotics into the United States annually, making marijuana, heroin, cocaine, and methamphetamines some of Mexico's most lucrative exports.
Blame the alleged corruption of some Mexican officials. Blame the deepening disparity between the two nations' economies, or the North American Free Trade Agreement (NAFTA). Blame the porous border, or the unquenchable appetite for drugs in America.
In the end, though, only one thing seems certain: Mexico and the United States are entering an unknown chapter in the history of nations - where sovereignty and the rule of law collide, more forcefully than ever, with the realities of a global economy.
"There's been a convergence of forces that have brought the problems of Mexico and the border into focus," says Roy Godson, a professor at Georgetown University. "It's not just drugs, but it also involves the movement of people, goods, and money. We're starting to see the seamy side of globalization."
The shadowy economic connection between Mexico and the US is hardly new. As long as there has been a border, smugglers have used its 2,000-mile expanse to traffic everything from cattle, guns, and liquor to cars, refrigerators, and jewelry.
In the last several decades, observers say, narcotics have assumed a far larger share of this covert commerce. One reason, surely, is the passion for cocaine that exploded in the 1980s, and more recently, the surge of heroin, marijuana, and methamphetamine use among youths.
But it's not that simple.
Much of the growth in drug smuggling has been fueled by international treaties like the General Agreement on Tariffs and Trade (GATT) and the NAFTA accord.
According to Ray Sadler, a history professor at New Mexico State University, Mexico's decision to join GATT in 1987 led to the elimination of many of its prohibitive trade tariffs, leaving scores of common smugglers, or "iguanas," with little demand for the microwaves and watches they'd been peddling. Many of them, he contends, simply turned to the drug trade.
"One unintended result of GATT," Dr. Sadler says, "was to provide a ready-made smuggling network" at a time when US drug demand was booming.
Likewise, experts note, the 1994 NAFTA accord has increased legitimate border traffic, swamping US customs officers at border checkpoints. As a result, officers say, they can only search about 7 percent of all vehicles crossing the border.
Although there's no telling how much more contraband is making its way through these legitimate routes, seizure totals at busy checkpoints have risen steadily. At the McAllen, Texas, border station, for example, agents seized 176,000 pounds of marijuana last year: 20 percent more than they intercepted in 1993.
Indeed, the US has steadily tightened the reigns on the Mexican drug trade in recent years. The number of border patrol and customs agents and the budgets of their respective agencies have risen significantly. Clinton's 1998 budget request seeks to add 500 more border patrol agents, and his proposed drug policies focus on decreasing the demand for drugs.
But US efforts must keep pace with the transformation taking place in the drug trafficking business. According to Peter Lupsha, a University of New Mexico political scientist, efforts to stanch the flow of drugs from the Caribbean to Florida have persuaded South American drug cartels to ship cocaine and heroin through Mexico.
Mexican traffickers, Dr. Lupsha says, have entered agreements to smuggle narcotics for the Colombian Cali and Medellin cartels across the US southwest border. As a result, he adds, the decades-old Mexican trafficking apparatus has been cast to the winds, with rival factions fighting each other for dominance.
The chaos has been fueled, Lupsha says, by the recent drug-related arrest and conviction of reputed Mexican trafficker Juan Garcia Abrego in Houston. As Mr. Abrego's organization has splintered into factions, he says, more independent traffickers have asserted themselves.
"There's a lot of fluidity at the moment," Lupsha says. "The more disorganized organized crime gets, the more competition you see, which always leads to violence."
THERE were more than 300 drug-related murders in Tijuana this year, Lupsha notes, and more than 200 in Juarez, Mexico. The new breed of drug trafficker, he says, is more aggressive and less concerned about American authorities. "You see a lot more brazen behavior, a lot more traffickers who just come across the border with no concern about camouflage. They have a sense they can get away with it."
According to US customs and border patrol agents at several locations, traffickers are going to extraordinary lengths to move their products: constructing secret compartments in 18-wheelers, saturating areas with hundreds of "mules" carrying backpacks with 40 kilos of marijuana each, and even, they believe, sacrificing large loads of marijuana at the border to allow more valuable shipments of heroin and cocaine to slip through behind them.
Allegations that Mexican officials are cooperating with drug traffickers have fueled speculation that Mexicans are losing control of their political and economic destiny. "Every institution in Mexico is under attack," Sadler says. "It's alarming. I hope it's not the beginning of the 'Colombianization' of Mexico - where the country simply falls into the hands of the cartels."