An increasingly urgent subject of scholarly research focuses on management of the United States–Mexico border, and its complex problems of immigration, narcotic smuggling, violence, binational commerce, global manufacturing and transnational pollution. While many of these issues are tied to the larger relationship between the United States and Mexico, the place where those challenges are embodied (and often explosively) is at the international border itself, a region that has over 15 million inhabitants living in cities on either side of its nearly 2,000-mile span. Of course, the border is also currently the focus of a volatile political debate at both the national and regional levels, especially in the United States.

In James Gerber's Border Economies, the author, an economist and recognised border scholar, states up front that he wishes to apply the theoretical and analytical lens of an economist to the border question, because, in his words, ‘Economists have had much less to say about the border than other disciplines, and it seemed like it was time for an economic view’ (p. x). His book, he offers, will be a pragmatic approach, using both economic history and theory to unravel some of the thorny problems facing the boundary zone.

This is a book that every border scholar (as well as Latin Americanists) should read. Ironically, the book's central purported goal – to measure whether there is ‘economic integration’ across the border – was not entirely convincing to this non-economist. I will return to that point below. But, to paraphrase the words of the poet Ralph Waldo Emerson, sometimes the journey is more important than the goal we imagine it is leading toward. In this case, the chapters leading up to the climactic ‘economic integration’ chapter, as well as those beyond, are superbly written, original and full of useful details that deeply enhance our understanding of the United States–Mexico border. The book is concise, yet comprehensive, and it achieves something rare in academic writing: it manages to be elegant in its prose, yet also respectful of academic theory and scholarly rigor.

Returning to the book's journey, the essence of the book, in my mind, lies in its subtitle: ‘Cities Bridging the U.S.–Mexico Divide’. Gerber's approach is to, first, analyse the scale of economic interactions between twin cities (Part I), then study the history of various border urban economies (Part II), the dilemmas of interaction (Part III), then, an economic analysis of border interaction (Part IV), and what those results mean for the future (Part V).

Gerber uses Part I to define the ‘twin cities’ along the border, as units of economic interaction, measured at the scale of urbanised counties on the US side and municipalities across the border in Mexico, as he explains in the opening chapter. Chapter 2, ‘Crossing the Border’, skilfully maps out the diverse array of cross-border flows that define the transnational economy – shoppers, tourists, workers, school children, medical visitors, and so forth.

The author poses Parts II and III as conceptual stage sets for the goal of measuring ‘economic integration’; they also stand alone as one of the very best recent analytical portraits of the complex United States–Mexico cross-border socio-economic ecosystem. Part II, ‘Historical Narratives of Economic Interdependence’, outlines the histories of the transnational border through the lens of tourism (Chapter 3), agriculture and water (Chapter 4), trade (Chapter 5) and manufacturing (Chapter 6). Here is where Gerber's command of border scholarship is especially masterful. For example, in the chapter on the history of border tourism, we hear about the ethical and racial conflicts that tourism unleashed as the era of prohibition and moral reform on one side of the border collided with the marketing of tourism on the other. Chapter 4 weaves an original narrative on water politics and cotton farming in the borderlands, and their critical legacy in the evolution of international treaties and governmental organisations to manage water around the boundary.

Equally compelling are Chapters 5 and 6, dealing with trade policy and manufacturing, respectively. Chapter 5 makes the clever argument that, when it comes to the trade economy, ‘dependency theory’ has it backwards along the Mexico–United States border. Traditionally, one would expect that Mexico is dependent on the more powerful US economy, yet US border cities, the author demonstrates, depend on policies and conditions in Mexico, where the flow of consumers of US retail goods is an essential part of the US border economy. Peso devaluations reinforce his argument. Chapter 6 summarises literature on the critical question of Mexico's maquiladora industry (assembly plant programme), and whether it has been good for Mexico's economy.

Part III addresses the two ‘dilemmas of interdependence,’ namely, immigration/security and drugs/smuggling. These both directly and indirectly impact the cross-border economy, and are important to the book since they are, as the author notes, dilemmas that must be managed, though, in both cases, there are no easy solutions.

Part IV is where Gerber presents an economist's framework for twin city regions, including a methodology that measures whether their economies are really ‘integrated’. Chapter 9 is a cogent narrative that deconstructs the more general ‘integration’ question along the border. Importantly, the author concludes that ‘the question of economic integration in Tijuana and San Diego, or any twin city pair, has an answer that is defined by the way the question is asked and by the methodologies used to answer it’ (p. 165). Chapter 10 introduces the theory of economic convergence, and its relevance to the United States–Mexico border through the lens of international trade. And finally, Chapter 11 seeks to apply the economic theory of ‘convergence’ along the border, as a way of determining whether there is ‘economic integration’.

Gerber finds that twin city economic data do not demonstrate ‘convergence’, based on his metrics; and he therefore concludes that there is no ‘economic integration’ at the United States–Mexico border. We were cautioned back in Chapter 9 that different methodologies would yield varying results, so we might take the finding of ‘no economic integration’ with a grain of salt. We can surmise that the centuries of Spain's domination of Mexico's economy and the legacy of that colonialism (and dependency) left its imprint, and it will take more than the few decades of modernity for Mexico to more fully develop a border economy that can compete in a globalising world.

In the end, ‘convergence theory’, or not, cross-border interdependence is certainly growing, as Gerber reminds us in the concluding Chapter 12, ‘Looking Forward’. The author calls for a border problem-solving approach that draws on the lessons learned from the management of the border's ‘international public goods’. Specifically, he cites the International Boundary and Water Commission (IBWC), confirmed in the bilateral treaty of 1944. The IBWC is the one success story along the border, where a jointly created international governmental organisation (IGO) manages a collective public good – water, flowing in rivers that transcend the boundary line. Why not think about creating these kinds of IGOs to manage the other critical cross-border public goods – air, public health, public safety, movement of people and goods – that will define the future of the urbanised, ‘twin city’ cross-border regions of the future? This conclusion cleverly leaves the reader with much to ponder about the future of this complex international policy arena.