US-Mexico Border: Overview.

United States; Mexico

The border between the United States and Mexico has long been an important point of entry to the United States. Beginning in the 1990s and continuing into the twenty-first century, large numbers of people have entered the US without legal authorization, primarily from Mexico but also from El Salvador, Guatemala, and Honduras, among other countries, with the proportion of people coming from countries other than Mexico generally increasing throughout the twenty-first century. By some estimates, this is the largest single wave of immigration into the United States recorded in the past two hundred years. However, the Pew Research Center reported that between 2009 and 2014, net migration from Mexico to the United States was negative, with more Mexicans leaving the United States than arriving. A 2016 report by the Center for Migration Studies found that since 1980, the legally resident Mexico-born population in the United States has grown faster than the undocumented population from Mexico. There were an estimated 10.9 million undocumented immigrants in the United States in 2014, continuing a leveling-off trend that followed a peak of 12.2 million in 2007.