Passage of California's Proposition 19, which aims to legalize recreational marijuana, could help ease the spiraling violence of Mexico's drug war.

Approval of the statewide ballot initiative on Nov. 2 would allow local governments to tax and regulate the limited possession and cultivation of marijuana for adults age 21 and over.

Besides offering the cash-strapped state a new source of revenue and jobs, Proposition 19 would also help pave the way for a much-needed drug policy shift south of the border.

In Mexico, turf battles between warring cartels and local authorities have turned wholesale massacres and brazen daytime shootouts into a daily occurrence.

The social and economic costs for California's southern neighbor are staggering.

Violence has claimed more than 28,000 lives since Mexican President Felipe Calderon took office in 2006. And his government has spent more than $10 billion in fighting the cartels - $1.4 billion of it from U.S. taxpayers. But to no avail.

Approval of Proposition 19 in California would help give Mexico the breathing room it needs for a fundamental course correction.

Last year, former presidents from Brazil, Colombia and Mexico issued a joint report, calling for a "paradigm shift" that includes the decriminalization of marijuana. "We need to break the taboo that's blocking an honest debate," they said.

Proposition 19 is helping reignite that debate.

The main destination for marijuana - and thus the main problem - remains the United States. The White House estimates that the Mexican cartels make 60 percent of their profits from marijuana. While some analysts say the number is inflated, the dollar value of the cross-border marijuana trade is undoubtedly worth billions.

Recently, a single marijuana shipment busted by Mexican authorities was alone valued at $340 million. This kind of money buys a lot of influence in Mexico.

As in the booze-running days of Al Capone, drug prohibition similarly drives the trade further underground, swelling the coffers of the violent narco-syndicates. Investigations by Mexican authorities have linked this financial clout to increasingly vast corruption networks in which police and local politicians are on the cartels' payroll.

Passage of Proposition 19 - and the possibility that other U.S. states might follow suit - would sap an important source of revenue for the drug traffickers, driving down both violence and corruption.

So, Proposition 19 is not just about allowing the recreational use of marijuana in California. It's also about the survival of Mexico.