legalizing drugs would cause the collapse of the cartels and help to end this violence.
https://qz.com/874497/mexico-is-moving-toward-medical-mariju... https://www.theguardian.com/world/2015/nov/18/former-preside...
Legalization implies regulation of some sort (e.g. like alcohol). You could also have a government-run monopoly.
The point is to remove the billions of dollars in black-market profits which give rise to criminal organizations who cannot depend on the law to resolve their disputes and must therefore "make their own law".