Immigration laws of United States have been immensely controversial in the recent decades. In contrast, international migration often arouses heated controversies and inflammatory rhetoric. That may seem odd in the context of the United States since we like to think of ourselves as a “nation of immigrants.” More people mean more pollution, more crime, more crowding, and more need for government services. Americans take pride in their immigrant history, but they are also concern about the impact of mass immigration, particularly when much of it seems to be illegal and uncontrollable. They are empathetic with immigrants, but they ...