The largest wave of immigration in history from a single country to the United States has come to a standstill. After four decades that brought 12 million current immigrants—most of whom came illegally—the net migration flow from Mexico to the United States has stopped and may have reversed.

The net standstill in Mexican-U.S. migration flow is the result of two opposite trend lines that have converged in recent years.

During the five-year period from 2005 to 2010, a total of 1.4 million Mexicans immigrated to the United States, down by more than half from the 3 million who had done so in the five-year period of 1995 to 2000.

Meantime, the number of Mexicans and their children who moved from the U.S. to Mexico between 2005 and 2010 rose to 1.4 million, roughly double the number who had done so in the five-year period a decade before. While it is not possible to say so with certainty, the trend lines within this latest five-year period suggest that return flow to Mexico probably exceeded the inflow from Mexico during the past year or two.

The standstill appears to be the result of many factors, including the weakened U.S. job and housing construction markets, heightened border enforcement, a rise in deportations, the growing dangers associated with illegal border crossings, the long-term decline in Mexico’s birth rates and broader economic conditions in Mexico. Read More

Russell Heimlich  is a former web developer at Pew Research Center.