Leah Boustan of Princeton and Maggie Peters of UCLA look at the wave of migrants to the US from Central America and compare it to the last great wave, from Europe in the late 19th century. Some things are the same: immigrant families are adopting "American" names at the same rates as before, for example. Some things are different: the speed of communication and container shipping mean that American companies prefer to get cheap labour through outsourcing, and won't lobby for increased immigration.