Carlos thought he’d be long gone by now. The young, college-educated New Yorker has been an illegal immigrant most his life. By last winter, a future with few options beyond washing dishes or working a factory assembly line had become too much for the gifted 24-year old to bear. Returning to his native Guatemala, he says, was not an option: “I have nothing there. I cannot go and adapt to that culture.” Staying also gave him the chance to be part of the presidential election, which he considers the most important event of his life. “If I was in Australia...