Political awareness of the tensions in U.S.-Mexico relations is rising in the twenty-first century; the American history of its treatment of illegal immigrants represents a massive failure of the promises of the American dream. This is the untold history of the United States Border Patrol from its beginnings in 1924 as a small peripheral outfit to its emergence as a large professional police force that continuously draws intense scrutiny and denunciations from political activism groups. To tell this story, MacArthur "Genius" Fellow Kelly Lytle Hernández dug through a gold mine of lost and unseen records and bits of biography stored in garages, closets, an abandoned factory, and in U.S. and Mexican archives. Focusing on the daily challenges of policing the Mexican border and bringing to light unexpected partners and forgotten dynamics, Migra! reveals how the U.S. Border Patrol translated the mandate for comprehensive migration control into a project of policing immigrants and undocumented “aliens” in the U.S.-Mexico borderlands.

This text provides an integrated view of post-9/11 security concerns over the United States's shared border with Mexico and Canada in regards to terrorism, unauthorized migration, drug and arms smuggling, and other illegal trade. The challenges facing U.S. Customs and Border Patrol are daunting. There are 19,841 miles of American land and water boundaries to protect, and 95,000 miles of shoreline and defined air space subject to homeland security surveillance. Additionally, the booming drug trade across the U.S.-Mexico border, combined with the ever-increasing number of migrants wanting to reach our land of opportunity, has resulted in a grim death toll: more than 5,000 known migrant deaths have occurred along the U.S.-Mexico border during 1995–2008, and in 2009, an estimated 9,635 Mexicans were killed in drug-related violence, with 2,573 people killed in Ciudad Juarez alone. U.S. Border Security focuses on the contrast between border security before and after the 9/11 terrorist attacks. This text also examines the controversial topics of illegal immigration, counterterrorism, drug and weapons trafficking, human smuggling, the impact of border security on the movement of people and goods, and the effect of the war on terrorism on civil and human rights.