The number of unauthorized immigrants in the U.S. fell to its lowest level in more than a decade, according to new Pew Research Center estimates based on 2016 government data. The decline is due almost entirely to a sharp decrease in the number of Mexicans entering the country without authorization.

But the Mexican border remains a pathway for entry by growing numbers of unauthorized immigrants from El Salvador, Guatemala and Honduras. Because of them, Central America was the only birth region accounting for more U.S. unauthorized immigrants in 2016 than in 2007.

There were 10.7 million unauthorized immigrants living in the U.S. in 2016, down from a peak of 12.2 million in 2007, according to the new estimates.