The number of Mexican unauthorized immigrants in the United States declined so sharply over the past decade that they no longer are the majority of those living in the country illegally, according to new Pew Research Center estimates based on government data. In 2017, there were 10.5 million unauthorized immigrants in the U.S., including 4.9 million Mexicans.

The decrease in the Mexican born was the major factor driving down the overall population of unauthorized immigrants in the U.S., which in 2017 was 1.7 million below its peak of 12.2 million in 2007.

The number of Mexican unauthorized immigrants declined because more left the U.S. than arrived. Mexicans remain a much larger percentage of all unauthorized immigrants than those from any other birth country. But their 47% share of U.S. unauthorized immigrants in 2017 amounted to less than a majority for the first time since the beginning of a long era of growth in illegal immigration a half century ago.