It was three years ago, early morning, when Elizabeth Perez returned to her Cleveland home from the doctor’s office with good news to tell her husband, Marcos: She was pregnant with their second child. For several moments, they celebrated with kisses, hugs, and tears of joy. Mr. Perez headed to work. A few minutes later, he was pulled over for a traffic-stop violation. Less than a month later, he was deported to Mexico City. “Noooooo!” Mrs. Perez wailed into the phone receiver when immigration authorities called to inform her that her husband had been apprehended. Mr. Perez would not be...