Sixteen-year-old Juan Pablo Lopez’s trip to the United States began in a semi-trailer, packed with 150 human beings. He thought it would end for him alone in a cramped cell at the Juvenile Detention Center in Globe, Ariz.

“I was thinking, ‘What are these people going to do to me?’” Lopez said at a recent interview in the District of Columbia. “I didn’t speak English and the guards didn’t speak Spanish. My family thought I was dead. I thought I was going to die.”