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Every minute, the US and Mexico trade $1 million in things like cars and corn across the busiest land border in the world. Mexico is the top destination for exports from Texas, Arizona, and California under the North American Free Trade Agreement or Nafta - a pact that Donald Trump calls the worst deal in the world and has threatened to rip up. But there's more than just flat screen TVs and avocados heading north, and gasoline and electronic goods heading south. Those same three states are also the biggest suppliers of one of Mexico's top illegal imports - guns.
And they, in turn, are a key destination for one of its most lucrative exports - drugs. There are no reliable up-to-date figures about how much the trade in drugs is worth. But we can make an educated guess that it's growing - fast. Mexican heroin seizures in the US have soared a whopping 1,760% since Nafta began nearly a quarter of a century ago. That's more than twice as fast as Mexico's legal exports to the US have grown in that time.
Cars are Mexico's most lucrative legal export. And the industry has been booming. Yet, vehicle production in Mexico increased only 2% last year. By contrast, the US believes Mexican production of heroin rose 16% in 2016. Or, to put that another way, Mexican exports make up only 14% of cars on US roads, but 93% of the heroin seized on US streets.
It's not just heroin. Mexican cartels have piled into methamphetamines, cocaines, and opioids that are mostly smuggled in cars, trucks, or buses - or via tunnels under the border. While drugs are flowing north, guns are pouring south - as many as 2,000 a day. That's about 200 wheelbarrows full every 24 hours. Around half are AK-47 type weapons and rifles.
While Mexicans can only legally buy arms from one military-run shop - its whereabouts is not public - 70% of the guns seized in Mexico was sold legally in the US before being trafficked over the border. Under Nafta, the US and Mexico have not just bought each other's goods. They have made them together. Car parts, for example, typically cross the border multiple times before being made into a finished car. And like the Nafta supply chains, officials say weapon components are now being transported south of the border to be assembled into guns in Mexico.
Donald Trump's answer is to build a wall. That might deter migrants, long one of Mexico's biggest illegal exports. But migrant flows are already at lows not seen since the 1970s. With rising demand, robust supply, and billions of profits at stake, whatever happens to Nafta, there's no end in sight to trade in drugs and guns.
