Executive Summary The International Organization of Migration has characterized the US-Mexico border as the world’s deadliest land migration route. By August 2024, a minimum of 5,405 persons had died or gone missing along this border since 2014, with record high numbers since 2021. Migrant deaths occur despite decades of: US Border Patrol search and rescue initiatives; public education campaigns targeting potential migrants on the dangers of irregular migration; dozens of academic publications and reports highlighting the root causes of these deaths; efforts by consular officials, local communities, and humanitarian agencies to locate, identify, and repatriate human remains; and desperate attempts by families to learn the fate of their missing loved ones. This paper introduces a special edition of the Journal on Migration and Human Security (JMHS), which draws on original research and the expertise of medical examiners, forensic anthropologists, social scientists, and humanitarian organizations to examine this persistent human tragedy. Many of the authors investigate migrant deaths in their professional capacities. They identify the dead, return remains to family members, and champion reforms to prevent deaths and better account for the dead and missing. This JMHS special edition represents a collaboration between the University of Arizona’s Binational Migration Institute, the Center for Migration Studies of New York (CMSNY), and the Working Group on Mapping Migrant Deaths along the US Southwest Border. The Working Group includes scholars and practitioners from California, Arizona, New Mexico, Texas, and New York who have met monthly since October of 2021. The special edition examines in granular detail the causes of migrant deaths, US border enforcement strategies and tactics, migrant death statistics, and the resource and capacity challenges faced by US counties along and leading from the US-Mexico border in investigating these deaths. The US Department of Homeland Security (DHS) and many public officials attribute the deaths to the predations of human smugglers, the victims’ ignorance or assumption of risk, and the harsh “natural” conditions to which migrants finally succumb. This special issue also documents the underlying non-natural causes of this enduring tragedy, and offers both overarching and more targeted solutions to preventing and minimizing migrant deaths. The issue builds upon and extends seminal research on migrant deaths first featured in CMSNY publications more than two decades ago. Section I introduces the issue of migrant deaths by posing the question: Why should we care? Section II describes the genesis of “prevention through deterrence”—a border enforcement theory and strategy—and its evolution through subsequent Customs and Border Protection (CBP) and US Border Patrol strategic plans. It describes the immense enforcement infrastructure built around this idea by successive administrations and Congresses, and it explains why it has failed to stem irregular migration and how it has contributed to migrant deaths. Section III reviews the main causes of migrant deaths—forced migration, the combined effects of prevention through deterrence and border enforcement tactics, the denial of access to asylum, the border wall, the “naturalization” of migrant deaths, and the dominant vision of the border as a site of danger and exclusion. Section IV reviews the legislative standards for identifying, investigating, and reporting on migrant decedents. It also details the deficiencies of Border Patrol and county-level sources of data on deaths, and it outlines ways to strengthen data collection. Section V discusses the burdens placed on communities along and leading from the border in investigating deaths and their need for greater resources and capacity to address this problem. Section VI outlines the anomalies and challenges related to the Border Patrol’s migrant rescue program. Section VII describes international legal standards to guide the investigation of migrant deaths and two model programs. Section VIII sets forth policy recommendations to prevent migrant deaths and to honor and account for the dead.