From the Background: "Mexico, along with the United States, is experiencing a surge in unauthorized migration from the 'Northern Triangle'of Central America (El Salvador, Guatemala, and Honduras). U.S. and Mexican officials are struggling to deal with high numbers of family units and unaccompanied minors, many of whom are seeking asylum. As the Trump Administration has tightened migrant access to the asylum system, Mexico has absorbed increasing numbers of Central Americans and others in need of humanitarian protection (see Figure 1). To avoid U.S. tariffs, the Mexican government agreed on June 7, 2019, to remove (deport) more migrants and allow more asylum seekers to await their U.S. asylum proceedings in Mexico."
CRS In Focus, IF10215
Congressional Research Service: https://crsreports.congress.gov/