True, if the U.S. would stop smuggling Drugs, quite a few Countries would have a decent Drop in their Crimes..
No Profit from Drugs = No Cartels...
Not just Mexico though, but also Columbia, Afghanistan, Panama, etc etc...
Although, other "rich" countries, like Netherlands, England, Germany etc etc, also "order" drugs...

And, considering just how easy it is to Buy Guns in the U.S. (and smuggle off the Border), we might also wanna consider figuring that out as well.

Then there's the Pharmaceutical issue, from somewhere the Legal purveyors of Opium have to get their Source, or else we wouldn't have Morphine, Vicodin, Oxycodone etc..
Oh, right, and lets not forget another Profitable Crime in Smuggling...
Exotic Animals {Someone once tried to smuggle a few "big cats" across U.S./Mexican Border}
And Human trafficking...
There's always something to smuggle, and profit from