Author Katherine Benton-Cohen, Assistant Professor of History, Georgetown University and Fellow, Woodrow Wilson Center; Eric Arnesen, Professor of History, George Washington University; Melanie Shell-Weiss, Visiting Assistant Professor of History, Johns Hopkins University

In American popular culture, conflict over the border between the U.S. and Mexico flared up throughout the 19th century but was resolved by the 20th. Not so, says historian Katherine Benton-Cohen in her provocative new book. Borderline Americans describes the 1917 clash between vigilantes and "undesirables"—immigrants, union activists, and others—in remote Cochise County, Arizona. This clash was, according to Benton-Cohen. "part of a larger national saga of race, belonging and exclusion." Her analysis has important implications for the present, when self-appointed Minutemen patrol the border where vigilantes once held sway.