Recent numbers from the U.S. Customs and Border Patrol are showing a huge decrease of drugs coming across the border. Since legalization began, most illegal drugs smuggled across from Mexico were steadily dropping. Now, there is proof that it is having an impact on cartel activity.
The statistics show that since 2012, meth, Fentanyl, and marijuana have all seen a drop in number of seizures. In 2017, heroin and cocaine began to fall as well. The data definitively shows an increase in legal status and a decrease in drugs being seized.
Legal status in the United States seems to be having a major impact on business for Mexican drug cartels. As more states legalize, we can expect to see this trend continue.
sources
https://www.civilized.life/articles/marijuana-legalization-hurting-cartels/
http://www.latimes.com/world/mexico-americas/la-fg-mexico-marijuana-20180127-story.html