A central thesis of border studies is that in contrast to the public perception of international boundaries, which sees them only as partitions, borders are complicated regions that bind as much as they separate and connect as much as they divide. Nichols's contribution to this scholarship is to chronicle the role that “mobile people played in the elaboration of the borderlands, [the ways in which they set off] national and local actors … from one another, and [how they shaped the] making of the border between two distinct nations” (10). In other words, Nichols's narrative does not have a top-down emphasis, but instead provides a picture from below in which individuals use the border for their own purposes and in so doing shape both nationalism and its geographical manifestation.

Given the current political context, for non-experts in the particular time period or the borderlands at large, this book is timely scholarship that makes several important points. First, the control of human flows has always been at the top of the agenda of both Mexico and the United States. Second, the violation of the law at the border is not some modern manifestation, but a constant throughout its history. The difference is that it often occurred in reverse to what we expect today, as when, for instance, Americans illegally pursued former enslaved people in Mexican territory. Likewise, contrary to the belief “that leaky borders … are the result of insufficient attention from the state, [and] that somehow resources or even a giant wall can fix the problem,” Nichols shows that “borders by their nature leak, no matter how many resources governments expend to stop the flow of unauthorized border crossers” (8).

For scholars familiar with the literature, the book also has much to offer. First, it gives a rather comprehensive account of transnational people not often considered together. These include various groups of indigenous peoples, runaway slaves, Mexican debt peons, and cattle rustlers, and the individuals that attempted to restrict their mobility, including vigilantes, Texas Rangers, Mexican militias, and so on. In doing so, Nichols is able to paint a much more powerful and broader transnational narrative than do authors of similar works. Second, the book documents well how this mobility shaped the nationalist rhetoric on both sides of the border. In other words, the significance individuals gave to the international boundary, an act quite apart from the intents of authorities on both sides, shaped not just how the states viewed themselves, but even to some extent their aspirations and the extent to which they should cooperate with the other. Related to this, Nichols shows well how the border could hold multiple meanings simultaneously and be both hard and soft at the same time as state control differed depending on the people involved.

Leaving a reader wanting more is not always a sign of a book's strength, but in this case, it clearly is. Nichols's narrative uncovers much within a relatively narrow geographical area (the Texas-Mexico border) and just as reduced a time period (roughly the 1830s to the 1860s), so reading it one is left wondering how this dynamic played out along the entire international boundary. How did having a less clearly defined partition further west along the border shape the mobility of the peoples Nichols references? One is left to speculate. The same is true for how this changed overtime. How and why did the various human flows documented in the book shift, and what does that tell us about borders writ large and about the state consolidation of both Mexico and the United States? Indeed, although I am certain that there were both practical and theoretical reasons for limiting the scope of the book, this is never made explicit. Future work might help answer those questions, but in the meantime, this is a compelling book that deserves your attention.