The sharp downward trend in net migration from Mexico began about five years ago and has led to the first significant decrease in at least two decades in the unauthorized Mexican population. As of 2011, some 6.1 million unauthorized Mexican immigrants were living in the U.S., down from a peak of nearly 7 million in 2007, according to Pew Hispanic Center estimates based on data from the U.S. Census Bureau. Over the same period, the population of authorized immigrants from Mexico rose modestly, from 5.6 million in 2007 to 5.8 million in 2011.