With the media and political commentators focused on family separation at the U.S.-Mexico border, few are paying attention to how developments along Mexico's southern border affect the United States. On Monday, Benjamin Wittes spoke with Stephanie Leutert, director of the Mexico Security Initiative at The University of Texas at Austin, who has spent the past several weeks in the field studying the flow of migrants from Central America into Mexico. They discussed who's entering Mexico, why they're doing it, why most continue on to the United States, and where the dangers lie along their journeys.