Maribel Navarro remembers a time, not so long ago, when afternoons at La Perla restaurant in the remote border settlement of Sásabe, on the Arizona-Mexico border, meant crowded tables and queues stretching out of the door.

The truck-loads of Mexican and central American migrants who descended on Sásabe en route to the US provided enough business not only for Ms Navarro but for the whole community. Some estimates suggest that more than 1,000 migrants - between a third and a half of the total number - passed through Sásabe daily.