In his new book, Matthew Longo takes the reader on an unusual journey, at least within political theory, since his work combines a normative political theory approach with an ethnographic approach to understand both the conceptual and actual issue of borders as spaces that separate and distinguish states and nations, and individuals and citizens. The Politics of Borders: Sovereignty, Security, and the Citizen after 9/11 (Cambridge University Press, 2017) is not simply about the border because, as the book makes clear, borders are in no way simple, and what Longo has pursued in his work is the complexity that encompasses the theoretical idea of the border but also how and why borders are more diverse in understanding than we often ascribe to them. Longo interrogates what a border actually is, noting that the space itself is not quite the thin line between states that we often assume it to be, but a physical area that is co-administered by bordering nations, often collaboratively, thus blurring the line or space of sovereignty. Threaded throughout the book is the ongoing question of what constitutes citizenship, since borders and citizenship are braided together though the structures of the state, and the considerations of who is and is not permitted membership within a state. Longo has also included a substantial exploration of the role of technology and data in the actual understanding of how border security works in practice. This section of the analysis is particularly important to consider because, according to Longo, the focus on the individual and their data profile, shifts the understanding of state sovereignty and the responsibility for definitions of citizenship. This book is incredibly topical in a variety of areas, not least in the way that it contributes to our thinking about the border itself as a space and as a concept, the role of the state, and the growing domain of data and technology and how they are shaping ideas of citizenship.This podcast was hosted by Lilly Goren, Professor of Political Science and Global Studies at Carroll University in Waukesha, WI. You can follow her on Twitter @gorenlj.