Mob violence in the United States is usually associated with the southern lynch mobs who terrorized African Americans during the Jim Crow era. In Forgotten Dead, William D. Carrigan and Clive Webb uncover a comparatively neglected chapter in the story of American racial violence, the lynching of persons of Mexican origin or descent. Over eight decades lynch mobs murdered hundreds of Mexicans, mostly in the American Southwest. Racial prejudice, a lack of respect for local courts, and economic competition all fueled the actions of the mob. Sometimes ordinary citizens committed these acts because of the alleged failure of the criminal justice system; other times the culprits were law enforcement officers themselves. Violence also occurred against the backdrop of continuing tensions along the border between the United States and Mexico aggravated by criminal raids, military escalation, and political revolution.

Based on Spanish and English archival documents from both sides of the border, Forgotten Dead explores through detailed case studies the characteristics and causes of mob violence against Mexicans across time and place. It also relates the numerous acts of resistance by Mexicans, including armed self-defense, crusading journalism, and lobbying by diplomats who pressured the United States to honor its rhetorical commitment to democracy. Finally, it contains the first-ever inventory of Mexican victims of mob violence in the United States.

Carrigan and Webb assess how Mexican lynching victims came in the minds of many Americans to be the "forgotten dead" and provide a timely account of Latinos' historical struggle for recognition of civil and human rights.