Exactly as Cato adjunct Jeffry Miron suggested, American marijuana reform has been bringing big changes to Mexico:

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.”

That’s actually great news: along with the big profits, marijuana brought northern Mexico tens of thousands of murders. We can all do without those.

One possible negative consequence has been an observed increase in Mexican opium production, although it may be too soon to say whether opiate use is really on the rise, and if so, whether it’s been driven by a greater availability of heroin, or by the government cracking down harder on prescription opiate addicts.

Of course, the answer to that problem resembles the answer to our marijuana problem, and both resemble the way we finally stopped bootleggers under alcohol Prohibition: legalize, establish relatively sensible regulations, and let addicts get treatment in an environment free of fear and threat. One doesn’t have to be a Harvard economist to see why that approach makes sense.