AMERICAN elections are watched closely in Mexico, which sends most of its exports and about a tenth of its citizens north of the border. But Tuesday’s presidential contest is not the only poll that’s sparking interest south of the Rio Grande. On the same day, voters in Colorado, Oregon and Washington will vote on whether to legalise marijuana—not just for medical use, but for fun and profit. Polls suggest that the initiatives have a decent chance of passing in Washington and Colorado (Oregon is a longer shot).

The impact on Mexico could be profound. Between 40% and 70% of American pot is reckoned to be grown in Mexico.