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—more than half of whom came illegally—the net migration flow from Mexico to the United States has stopped—and may have reversed, according to a new analysis by the Pew Hispanic Center of multiple government data sets from both countries.

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 changing economic conditions in Mexico.

The report is based on the Center’s analysis of data from five different Mexican government sources and four U.S. government sources. The Mexican data come from the Mexican Decennial Censuses (Censos de Población y Vivienda), the Mexican Population Counts (Conteos de Población y Vivienda), the National Survey of Demographic Dynamics (Encuesta Nacional de la Dinámica Demográfica or ENADID), the National Survey of Occupation and Employment (Encuesta Nacional de Ocupación y Empleo or ENOE), and the Survey on Migration at the Northern Border of Mexico (Encuesta sobre Migración en la Frontera Norte de México or EMIF-Norte). The U.S. data come from the 2010 Census, the American Community Survey, the Current Population Survey and the U.S. Department of Homeland Security.

Among the report’s key findings:

• In the five-year period from 2005 to 2010, about 1.4 million Mexicans immigrated to the United States and about 1.4 million Mexican immigrants and their U.S.-born children moved from the United States to Mexico.
• In the five-year period a decade earlier (1995 to 2000), about 3 million Mexicans had immigrated to the U.S. and fewer than 700,000 Mexicans and their U.S. born-children had moved from the U.S. to Mexico.
• This sharp downward trend in net migration has led to the first significant decrease in at least two decades in the number of unauthorized Mexican immigrants living in the U.S.—to 6.1 million in 2011, down from a peak of nearly 7 million in 2007. Over the same period the number of authorized Mexican immigrants rose modestly, from 5.6 million in 2007 to 5.8 million in 2011.
• Mexicans now comprise about 58% of the unauthorized immigrants living in the United States. They also account for 30% of all U.S. immigrants. The next largest country of origin for U.S. immigrants, China, accounts for just 5% of the nation’s stock of nearly 40 million immigrants.
• Apprehensions of Mexicans trying to cross the border illegally have plummeted by more than 70% in recent years, from more than 1 million in 2005 to 286,000 in 2011—a likely indication that fewer unauthorized immigrants are trying to cross. This decline has occurred at a time when funding in the U.S. for border enforcement—including more agents and more fencing—has risen sharply.
• As apprehensions at the border have declined, deportations of unauthorized Mexican immigrants—some of them picked up at work or after being arrested for other criminal violations—have risen to record levels. In 2010, nearly 400,000 unauthorized immigrants—73% of them Mexicans—were deported by U.S. authorities.
• Although most unauthorized Mexican immigrants sent home by U.S. authorities say they plan to try to return, a growing share say they will not try to come back to the U.S. According to a survey by Mexican authorities of repatriated immigrants, 20% of labor migrants in 2010 said they would not return, compared with just 7% in 2005.
• Looking back over the entire span of U.S. history, no country has ever sent as many immigrants to this country as Mexico has in the past four decades.

Source: Pew Research Center