Geography

The number of Mexican immigrants living illegally in the U.S. has dropped significantly for the first time in decades, a dramatic shift as many illegal workers, already in the U.S. and seeing few job opportunities, return to Mexico. An analysis of census data from the U.S. and Mexican governments details the movement to and from Mexico, a nation accounting for nearly 60 percent of the illegal immigrants in the U.S. It comes amid renewed debate over U.S. immigration policy as the Supreme Court hears arguments this week on Arizona's tough immigration law. Roughly 6.1 million unauthorized Mexican immigrants were living in the U.S. last year, down from a peak of nearly 7 million in 2007, according to the Pew Hispanic Center study released Monday. It was the biggest sustained drop in modern history, believed to be surpassed in scale only by losses in the Mexican-born U.S. population during the Great Depression. Much of the drop in illegal immigrants is due to the persistently weak U.S. economy, which has shrunk construction and service-sector jobs attractive to Mexican workers following the housing bust. But increased deportations, heightened U.S. patrols and violence along the border also have played a role, as well as demographic changes, such as Mexico's declining birth rate. In all, the Mexican-born population in the U.S. last year — legal and illegal — fell to 12 million, marking an end to an immigration boom dating back to the 1970s, when foreign-born residents from Mexico stood at 760,000. The 2007 peak was 12.6 million. About 1.4 million Mexicans left the U.S. between 2005 and 2010, double the number who did so a decade earlier. In the meantime, the number of Mexicans who entered the U.S. sharply fell to about 1.4 million, putting net migration from Mexico at a standstill. More recent data suggest that most of the movement is now heading back to Mexico, accounting for the drop in the illegal immigrant population. During the same period, the population of...