Migration at the U.S.-Mexico Border: A Challenge Decades in the Making

U.S.-Mexico border security has been a central policy matter and divisive political issue in the United States for decades. The U.S. border control enterprise has faced two distinctly different eras of unauthorized migration: The first, from the 1980s through the early 2010s, was addressing overwhelmingly Mexican seasonal adult flows. The current era has been marked first by a rise in arrivals of Central American children and families beginning in 2014, and most recently unprecedented flows of asylum seekers from Latin America and beyond. Earlier strategies that dramatically reduced the levels of illicit border crossings have been no match for the sharply diversified migration patterns of today, with the government struggling to adapt its policy and operational structures.

This report examines the history of the federal government’s efforts to improve southwest border security in the modern era, beginning with the Clinton administration in 1993 and looking at subsequent changes during the Bush, Obama, Trump, and Biden administrations. The study identifies key developments in the evolution of U.S.-Mexico border security, including the changing origins and characteristics of migrants arriving at the border.

The report also draws lessons from this long view of the border that may benefit policymakers and political leaders today. These include the necessity of recognizing how the Department of Homeland Security’s mission has evolved and how vital interagency partnerships are, and that a transnational phenomenon such as irregular migration requires policies and international partnerships that stretch far beyond the border line itself.