By CEDAR ATTANASIO and ELLIOT SPAGAT
Associated Press

EL PASO, Texas (AP) - U.S. authorities are overstretched and overwhelmed by an unprecedented surge of Central American families arriving at the southern border.

It is against that backdrop that President Donald Trump threatened this week to slap tariffs on goods from Mexico unless it cracks down on the flow of migrants.

On Wednesday, for example, Border Patrol agents near downtown El Paso, Texas, encountered a group of 1,036 migrants who had entered the country illegally - the biggest cluster the agency has ever seen.

At one point in May, a government holding cell designed for 35 migrants was crammed with 155.

And six children have died in U.S. custody since September, three in the past month.

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