From the 1970s to the early 2000s, the United States experienced an epochal wave of low-skilled immigration. Since the Great Recession, however, U.S. borders have become a far less active place when it comes to the net arrival of foreign workers. The number of undocumented immigrants has...

In this paper, I selectively review recent literature on illegal migration from Mexico to the United States. I begin by discussing methods for estimating stocks and flows of illegal migrants. While there is uncertainty about the size of the unauthorized population, new data sources make it...