The largest wave of immigration from a single county to the United States has reached a statistical standstill, as the net migration flow from Mexico has stopped, according to a report from the Pew Hispanic Center.

In 2011, there were 6.1 million illegal immigrants living in the U.S., down from a peak of nearly 7 million in 2007. Over the same period, the number of authorized Mexican immigrants rose from 5.6 million in 2007 to 5.8 million in 2011.

The center's report cites 2005 as the tipping point that began a five-year period when just as many Mexicans and their American-born children immigrated to Mexico as Mexican nationals immigrated to the U.S. About 1.4 million moved in either direction.

During the five-year period a decade earlier (from 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.

The standstill is a result of many factors, according to the report, 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.

Read the full report here .