Book excerpt: This second edition is an update of the intersection of border security, immigration, and assimilation in the U.S.A. In addition to the history of immigration and custom services and shifts in attitudes about immigration, this edition provides new information about the operations of the Department of Homeland Security to secure the border. A new chapter examines developments in immigration policy relating to the border wall, family separation, unaccompanied immigrant minors and Deferred Action for Childhood Arrivals or DACA. The book includes real-life stories of difficult incidents that arise due to the complicated relationship between immigration and border security. The authors review prospects for comprehensive immigration policy and border security policy.