Alvarez is interested in issues surrounding the history of the U.S.-Mexico border, U.S.-Mexico relations, and federal policing. His book, "The Shape of the Border: Policing the U.S.-Mexico Divide," explains how the U.S. and Mexican governments built the border as a space to facilitate the massive circulation of capital and how this process ultimately transformed the borderland into a zone of exceptionally high police presence and activity. His publications include “Inventing the U.S.-Mexico Border,” in James T. Sparrow, Stephen Sawyer, and William J. Novak, eds., "Boundaries of the State in U.S. History" (2015). He is currently working on another book, titled "The Shape of the Border: Policing the U.S.-Mexico Divide, 1848-2010."