Divided by the Wall: Progressive and Conservative Immigration Politics at the U.S.-Mexico Border (University of California Press, 2020) uses 20 months of immersive ethnography to examine why undocumented immigration has become such a polarizing topic. Its focus, however, does not rest on policy battles or policy outcomes. Instead, this is a compelling study of a group of grassroots pro-immigrant and anti-immigrant activists in Arizona, who are overwhelmingly white American citizens with no direct, personal stake in the immigration issue. Some leave water in Arizona’s Sonoran desert for migrants to find, while others, on the other side of the issue, conduct armed patrols to detect unauthorized border crossers. The book is animated by two puzzles: Why do these activists invest so much of their time and energy into a set of practices that are (a) first, not likely to benefit them or their loved ones, and, (b) second, highly limited in their effectiveness? By exploring the meanings that this mobilization holds for my research subjects, I show how immigration politics has become a substitute for struggles around class inequality among white Americans.