I’ve been screaming about this for almost a year now, and if you haven’t seen it for yourself first or second hand, you almost certainly will before long. I’m saddened to see the issue coupled to marijuana decriminalization, but I guess farmers have to get paid one way or the other.

The surge of cheap heroin spreading in $4 hits across rural America can be traced back to the remote valleys of the northern Sierra Madre.

With the wholesale price of marijuana falling — driven in part by decriminalization in sections of the United States — Mexican drug farmers are turning away from cannabis and filling their fields with opium poppies.

Mexican heroin is flooding north as U.S. authorities trying to contain an epidemic of prescription painkiller abuse have tightened controls on synthetic opiates such as hydrocodone and OxyContin. As the pills become more costly and difficult to obtain, Mexican trafficking organizations have found new markets for heroin in places such as Winchester, Va., and Brattleboro, Vt., where, until recently, needle use for narcotics was rare or unknown.

Farmers in the storied “Golden Triangle” region of Mexico’s Sinaloa state, which has produced the country’s most notorious gangsters and biggest marijuana harvests, say they are no longer planting the crop. Its wholesale price has collapsed in the past five years, from $100 per kilogram to less than $25.

“It’s not worth it anymore,” said Rodrigo Silla, 50, a lifelong cannabis farmer who said he couldn’t remember the last time his family and others in their tiny hamlet gave up growing mota. “I wish the Americans would stop with this legalization.”

Growers from this area and as far afield as Central America are sowing their plots with opium poppies, and large-scale operations are turning up in places where authorities have never seen them.

In late January, police in Honduras made their first discovery of a poppy farm in the country, raiding a sophisticated mountain greenhouse as big as a soccer field. That same week, soldiers and police in western Guatemala came under attack by farmers armed with clubs and gas bombs when the security personnel moved in to destroy 160 acres of poppy.

Along the border with Mexico, U.S. authorities seized 2,162 kilos of heroin last year, a record amount, up from 367 kilos in 2007.

The needle habit in the United States has made a strong comeback as heroin rushes into the country. Use of the drug in the United States increased 79 percent between 2007 and 2012, according to federal data, triggering a wave of overdose deaths and an “urgent and growing public health crisis,” Attorney General Eric H. Holder Jr. warned last month.

Although prescription painkillers remain more widely abused and account for far more fatal overdoses, heroin has been “moving all over the country and popping up in areas you didn’t see before,” said Carl Pike, a senior official in the Special Operations Division of the Drug Enforcement Administration.

With its low price and easy portability, heroin has reached beyond New York, Chicago and other places where it has long been available. Rural areas of New England, Appalachia and the Midwest are being hit especially hard, with cities such as Portland, Maine; St. Louis; and Oklahoma City struggling to cope with a new generation of addicts.

Pike and other DEA officials say the spread is the result of a shrewd marketing strategy developed by Mexican traffickers. They have targeted areas with the worst prescription pill abuse, sending heroin pushers to “set up right outside the methadone clinics,” one DEA agent said.

Some new heroin users begin by snorting the drug. But like addicts of synthetic painkillers who go from swallowing the pills to crushing and snorting them, they eventually turn to intravenous injection of heroin for a more powerful high. By then, experts say, they have crossed a psychological threshold — overcoming the stigma of needle use. At the same time, they face diminishing satisfaction from prescription pills that can cost $80 each on the street and whose effects wear off after four to six hours.

Those addicts are especially susceptible to high-grade heroin offered for as little as $4 a dose but with a narcotic payload that can top anything from a pharmacy.

The opioid epidemic is the biggest domestic health threat facing kids and young adults today. It’s a significant problem even for middle age folks. Even as heroin use and addiction is going through the roof, the overall problem is opioids of all types. People should not take opioids except as a last resort, and never unless they are suffering from debilitating pain. For too many people, opioid prescriptions lead to quick dependency, and there is literally nothing you’d less like to be than addicted to opioids.

Ironically, efforts to fix the prescription opioid problem have increased the attractiveness of heroin, and efforts to decriminalize marijuana have increased the supply of heroin. It feels like squeezing a balloon, where no matter what you succeed in doing, another equal or worse problem crops up somewhere else.