Six years had passed since Glenda Valdez kissed her toddler goodbye and left for the United States — six years since she held Emely in her arms. But here she was, at Texas’ Austin-Bergstrom International Airport, tearfully embracing the little girl she left behind. And it happened only because she had glimpsed a televised photo of Emely, part of an Associated Press story on young people crossing the Mexican border alone.