They have tried to stamp out cocaine for years. Governments have sprayed herbicides on fields of coca leaf. Police have raided the primitive laboratories that refine coca paste. Counternarcotics agents have seized and destroyed hundreds of tons of cocaine powder, arresting or killing thousands of smugglers.

Yet after 20 years and eradication programs totaling hundreds of millions of dollars, cocaine can be bought on every continent, in virtually every major city. The drug has even survived a market decline in which the number of regular cocaine users in the United States dropped, to 1.5 million in 1995 from 5.7 million a decade before. Americans are still snorting, smoking or injecting cocaine at the rate of 240 tons a year, almost all of it produced in Colombia and much of it smuggled through Mexico.

The debate that preceded the Clinton administration's decision on Friday to certify Mexico as an ally in its war against illegal drugs while decertifying Colombia underscored how deeply entrenched the cocaine habit has become, enmeshing South and North America in an intricate web of corruption and violence.

The reasons for cocaine's resilience are a matter of simple economics, as interviews with the people who make, sell, use and try to destroy cocaine confirm. It is a sweatshop industry that taps a limitless supply of cheap labor, generates enormous profits for a few and enjoys a base of addicted customers.

And just as any large and diffuse commercial enterprise is ultimately dependent on the favor or cooperation of officials and regulators, the cocaine trade is well oiled by corruption along the way. A draft analysis by American intelligence officials estimates that Mexican drug traffickers earn up to $10 billion a year and then dole out as much as $6 billion on bribes for Mexican officials and police officers.

The most powerful symbol of cocaine's resilience is the trail that the drug follows from leaf to crack and powder, from farmer to addict, from the Andean jungles to the New York City streets.

"For a narcotics trafficker, the most valuable asset is his route," said Gen. Rosso Juan Serrano, commander of the Colombian National Police, referring not just to the physical trail, but also to the clandestine airstrips, the hidden warehouses and corrupt officials like air controllers and police along the way. And as with an octopus that grows new tentacles when old ones are damaged or cut off, the trail sprouts new paths, means of transport and markets when the old ones are attacked.

Donald Ferrarone, the special agent in charge of the Federal Drug Enforcement Administration field office in Houston, has seen cocaine flowing in for years. "The only difference," Ferrarone said, "is the intensity is more ferocious now."

The trail starts in the Andean jungles, where peasants strip coca bushes of their oval leaves, dump the leaves in a plastic-lined pit and pour in kerosene or gasoline, water and, sometimes, sprinkle on cement.

Barefoot, the workers stomp the mixture to press out the psychoactive alkaloids into a paste that resembles grimy snow. Across rural Colombia, thousands of laborers process the paste into a sludge that is dried to form the raw ingredient for powdered cocaine hydrochloride.

Every day, more than two tons of powder flows through Mexico and the Caribbean, with one-third of that ending up in the United States. Once cocaine was ferried by small planes. Now, to evade American radar surveillance, more and more cocaine floats north in the holds of freighters, fishing boats and yachts.

"How are drugs coming across the border?" asked Leon Guinn, special agent in charge of the Customs Service field office in Houston. "Probably in every imaginable way you can think of."

Altemar Restrepo could not earn enough cutting sugar cane to support his family. So Restrepo, a slender Colombian, followed other peasants and apprenticed himself to the making of cocaine.

For 4 of his 25 years, Restrepo said, he has worked in the tangled jungle of southeastern Colombia, fetching the gasoline used to leach coca leaves of their alkaloids. The "cocina," or jungle laboratory where Restrepo was interviewed, consisted of six wooden maturation pens, in which a ton of leaves soaked in gasoline and water.

Every week, he said, the laboratory produced more than 75 pounds of coca to be refined elsewhere into powdered cocaine.

"We do this because you can't raise cattle or corn in this region," Restrepo said as he fidgeted, shirtless and sweating, beside a waist-high pile of coca leaves. "There's no water, and transport is too expensive."

As a cane cutter, he said, he was lucky to earn $35 a week. For processing coca leaves he was promised $10 to $15 a day, plus a dormitory cot and food. He has not been paid for three months, he said, and he misses his family several hundred miles to the north. He wants to go home.

Restrepo gave his account minutes after having been seized by Colombian narcotics police commandos who raided the laboratory, sending co-workers bolting into the jungle. He admitted having been arrested before. "I don't know who owns the patch and I don't ask," Restrepo said. "When I did ask, they said, 'Just keep working."'

The police ripped up the pens with a chainsaw and kicked over the metal drums, splattering coca base into the mud. When the officers tried to blow up what was left, the waterlogged leaves refused to ignite. The police retreated under the machine gun of a hovering helicopter, leaving Restrepo looking unperturbed.

"He said he had a family, so we couldn't leave his wife and children alone," Col. Leonardo Gallego, commander of the police unit, said. "I feel strongly about the plight of young men and children who get into drugs or fall in with drug-trafficking gangs."

Restrepo's employers got no such sympathy.

"They only commit crimes because of cruelty and personal gain," Gallego said. "There's no regard for the country or the views of the international community."

Because coca pays much better than pineapples or bananas and is easier to market, the farmers who grow it express few qualms about working for what they see as, ultimately, the Yankee dollar, though one such "cocalero," Franklin Gonzales, said he would rather sing.

But pop singing pays little. So Gonzales, a wiry 24-year-old, left his wife and young son and traveled southwest to the river town of Miraflores.

"I left them because of the violence here," he told a reporter.

He was making $30 or $40 a day tending coca fields until the National Police sprayed them with herbicide last summer. Now, Gonzales said: "It's hard. There is no money. There are people here, but not as many as before."

Coca production in Colombia created boom towns out of many backwaters like Miraflores, a ramshackle settlement of whitewashed houses with metal roofs along the muddy Vaupes River. The drug lords do not bother to visit, sending commercial agents to buy the paste openly from growers.

After coca had displaced rubber as the primary crop, Miraflores swelled to 10,000 inhabitants, 600 of them prostitutes, said the Rev. Manuel Mancera, the Roman Catholic priest in the town. Coca money built a new discotheque that glitters with mirrors. Fighting and whoring became nightly diversions.

"There were no values or principles," Mancera said. "People were too attached to money.'

Since the spraying, Miraflores has shriveled to a few thousand residents. The farmers are hard put to make a living, because they have no roads to carry legal crops to market.

"It's the beginning of the end of Miraflores," the priest said. "Because if it isn't coca, there is just no other produce."

The National Police reported that they sprayed 55,715 acres and destroyed 938 cocaine laboratories last year. But when towns like Miraflores die, traffickers find others, making alliances with leftist guerrillas who charge a tax according to the weight of cocaine passing through their territory.

The government cut off deliveries of gasoline and cement to the region after discovering that extensive quantities had been diverted to process coca leaves. Now, those materials are smuggled from Venezuela.

"You can't even get gasoline," said Estrela Contreras of Miraflores, who organized demonstrations against spraying. "We're all paying for the sins of a few."

The profits of cocaine are manifested in a two-story residence that rises like a fortress above an attractive neighborhood of Cali, a fashionable western city that is the home of the world's most prominent drug cartel.

The house, made of concrete, has no windows facing the street. But inside are marble floors, crystal chandeliers, furniture gilded and tasseled in Narco-Deco style and bowling lanes. The garden has an enormous swimming pool. A police specialist in the search party told an accompanying reporter that the house was worth $15 million.

The police and soldiers raided the house because its owner, Jose Orlando Henao Montoya, is suspected of being a rising drug trafficker. He was not home at the time.

The closets held barely a change of clothes. Family photographs had been stripped from silver frames. The maid said the family had left for its country ranch.

The searches began when the police, with discreet help from American agents, captured six leaders of the Cali cartel in 1995.

"They were very powerful," the commander of the search team, Lt. Col. Ramiro Villalobos, said. "People were afraid of all the bodyguards, the extravagant cars and the display of guns. This no longer happens. Now we can go out at night without fear."

But with some cartel leaders' running the business by telephone from prison and new independent traffickers' taking up the slack, has the output of cocaine been stanched?

Villalobos paused and replied, "We can't say it's less, no."

The bulk of the cocaine that enters the United States passes through Mexico, with the help of Mexican crime federations that demand up to half the Colombians' cocaine and heroin in return, the Drug Enforcement Administration said. The Mexicans distribute their share through their own networks.

"The Colombian narcotraffickers have very comfortable relations with the Mexican mafia," General Serrano of the Colombian police said. "It's almost a natural relationship."

The cocaine increasingly arrives in Mexico on vessels like the Don Celso. The rusty fishing boat, flying the Ecuadorean flag, ostensibly carried shrimp and tuna between Buenaventura, Colombia, and Manzanillo, Mexico. But Colombian and American agents who boarded her off Ecuador in October reported finding 12 tons of cocaine.

Once in Mexico, the cocaine is trucked north to the U.S. border, with the connivance of corrupt government officials, federal agents said. One agent said 30 to 40 tons of cocaine were stockpiled in Mexico, awaiting delivery to the United States.

Mexico's economic problems and double-digit unemployment help in recruiting smugglers for a relative pittance. One smuggler was offered $500 to smuggle a load to Los Angeles and promised another $500 if he made it back, an antidrug agent said.

Lose a load, however, and a smuggler can be forced to work for nothing to make it up, or the smuggler could be disfigured or killed.

"The level of violence is like nowhere I've ever seen," said a federal agent in Texas who insisted on anonymity.

The agent told of a woman who had been caught carrying drug profits back across the border. She agreed to turn informer and asked to go home to Juarez. She turned up garroted.

J.J. Lopez stood on the concrete Bridge of the Americas in El Paso, watching the flow of automobiles from Ciudad Juarez, a few hundred yards away. More than one million cars, many driven by commuters, cross between El Paso and Juarez each month, giving U.S. Customs inspectors a scant 10 or 15 seconds to look over each car.

"We have to move the traffic," Lopez, the chief customs inspector at the bridge, said. "But we also have to address the threat that we have, which is narcotics."

Lopez was watched by a young man who cradled the receiver of the nearest pay telephone, about 50 yards away. Nearby, his accomplice talked into a two-way radio as he surveyed the heavy traffic.

They were spotters, Lopez said, hired by the syndicate of Amado Carrillo Fuentes to tell smugglers which lanes to use or avoid. Spotters earn $25 to $50 a day for working the bridge, far more than the $25 to $40 a week that they might earn in a Juarez factory.

Customs inspectors conduct two-minute blitzes in which they stop and check every car in one lane or walk through traffic with dogs trained to sniff out drugs.

'We've had people bail out of their cars and run back" to Mexico, Lopez said.

To reduce chances of losing a major load, traffickers now move cocaine in quantities of a few hundred pounds. After crossing the border, loads are deposited at stash houses for consolidation.

Lopez said drugs were concealed deep inside vehicles, often behind electronic trapdoors. Inspectors have found cocaine replacing trailer insulation, inside tire rims and poured in the fuel tank to form a sediment to be scooped out later. Sixty pounds of cocaine can fit behind some dashboards, he said.

Cocaine has even turned up in a baby's diaper.

"Think of the sensitivity of searching an infant," said George McNenney, a customs special agent in El Paso.

Before dusk erased the shadows across the sagebrush, cactus and mesquite outside Eagle Pass, Texas, the rancher coaxed his Jeep to the rim of a bluff overlooking the Rio Grande. Rifle at hand, he watched for the smugglers who walk their loads across the placid river and onto his 165-acre spread.

No fences or barriers define the border here. As a teen-ager nearly 50 years ago, the rancher himself waded into the knee-deep water to play baseball with Mexican youngsters who lived on the other side.

"You can't do that now," he said.

The rancher would not allow his name to be used, fearing smugglers might retaliate.

"They're not looking for trouble," he said. "But if you run into them, they're armed and you don't have a chance."

He used to call Border Patrol agents in nearby Eagle Pass, he said, but before they arrived, the intruders would melt into the darkness. So now, he said, "my neighbors and I watch each other's backs."

A neighbor on the Mexican side, he said, had encountered on his land unmarked vans and an armed stranger who barred the way. A neighbor in Texas found night-vision goggles on a trail that crossed his property.

"My gates have been torn down, knocked up and run over," the rancher said, adding that his wife went to church alone on Sundays, because they dared not leave the ranch unattended. "Our place is valueless now. You can't give it away. You can't rent it."

In fact, ranches along the Rio Grande attract buyers ready to pay -- in cash -- more than the properties are worth. One spread worth barely $300,000 was bought for $850,000 by someone who was later traced to drug smuggling.

"We've had dopers come out and look at this place," the rancher said.

A realty agent asked the owners to leave while the client inspected. They refused.

Even with the billions spent to fight drugs, the rancher said, "it gets worse every year."

"I don't know what to do about it," he said. "But what we're doing doesn't work."

When powdered cocaine began to lose its appeal in the 1980s, distributors in cities like New York created a new market by cooking the powder with baking soda and water to make crack.

"Crack is still out there," said John Galea, who runs the Street Studies Unit of the New York state Office of Addiction and Substance Abuse Services. "We've noticed that 13- and 14-year-olds are not using it any more. But they're selling it."

Dealers in Brooklyn, N.Y., confirmed that the profits that built expensive houses in Cali did not trickle down to the sidewalks of New York. A teen-ager who was peddling crack said that he could take in $75 to $100 a day, but that he dared work just a few days a week, fearing he would attract the police.

Another seller said he made $25 for selling a bundle of 20 "nickel" bags for $5 each.

Crack's attraction for users lies in its instant high and cheap price. Powdered cocaine sells for $30 to $40 a gram in upper Manhattan. A pebble of crack costs $2 to $5.

Although crack is widely derided as a loser's drug, its customers include people like Thomas DeGrace, 35, who had a restaurant and a music company and whose five-year addiction wiped out all he had achieved.

"Crack is the only drug in the world where the more you take, the more you want," DeGrace said. "When you take your first hit, you're chasing that hit for the rest of the day."

Eventually, DeGrace lived on the street, bartering for crack by holding the drugs so the dealer could avoid arrest if the police swooped in.

"I came from a family that taught morals and standards, but that drug just takes them away from you," DeGrace said. "You see yourself diminish as a man."

He has entered a rehabilitation program run by Phoenix House.

If male addicts perform a dealer's stoop labor, women suffer worse humiliation.

"It degrades you to where you're selling your body," Cynthia McBride said. "That's where it started and ended with me."

Ms. McBride, 25, said she began sniffing cocaine as a 10-year-old to overcome stage fright when she sang soul music professionally. By the time she moved to crack, she said, "I was married, cheating on a husband and sleeping with men to get high."

Even after social workers had removed her five children, Ms. McBride said, she continued chasing crack.

"Physically, it shows on you," she said. "You're a walking skeleton if you're a crack head, and you think you look good."

Despite all the lipstick she smeared on, Ms. McBride said, she grew so scrawny that dealers refused to have sex with her. After she had slashed a rival prostitute, she, too, checked into Phoenix House.

"When the drug dealers start dissing you," she said, "when you can't get a $2 hit because they don't want you, that's when it's time to go."