Mexican manufacturers of illegal marijuana bricks have driven down prices as residents in California, Colorado, and Washington state now have safe access to reasonably affordable medical marijuana and/or recreational cannabis. Two or three years ago, a kilogram [2.
This has been true since 2015, the article is a little late. I think the new method is go send cartel illegals to NorCal(so easy now days), and grow in the US to avoid border crossing.
http://blog.sfgate.com/smellthetruth/2016/03/07/legal-marijuana-causes-mexican-drug-cartel-revenues-to-plummet/