President-elect Donald Trump has repeatedly called for Mexico to build a wall between our countries. There is indeed a way that Mexico could create a barrier between the U.S. and Mexico, one constructed exclusively on the Mexican side, with substantial benefits for both countries and the planet: a solar border.
Sunlight in the northern deserts of Mexico is more intense than in the U.S. Southwest because of the lower latitude and more favorable cloud patterns. And construction and maintenance costs for solar plants in Mexico are substantially lower. Thus, building a long series of such plants all along the Mexican side of the border could power cities on both sides faster and more cheaply than similar arrays built north of the border.