Book Review of Mau, Steffen 2023. Sorting Machines. The Reinvention of the Border in the 21st Century. Cambridge: Polity Press. 174 pp.

Steffen Mau’s Sorting Machines. The Reinvention of the Border in the 21st Century is a translation, by Nicola Barfoot, of Mau’s 2021 German book Sortiermaschinen: Die Neufindung der Grenze im 21. Jahrhundert. It can also be seen as an extension of some of his earlier work on borders and mobility, more specifically visa policies and mobility inequality, which both play central roles in the book (e.g., Mau et al. 2012; 2015).

In this relatively short book, Mau explores the changed function of borders in the 21st century through the lens of globalization. As stated in the first sentence of the book, Mau seeks to engage in the growing debate regarding territorial borders and border control in our globalized era. He starts by reviving the post-Berlin wall time where many believed that we were moving toward—if not already living in—a borderless world. However, as Mau explains, such hopes/fears have been exaggerated. Mau stands out from others in his way of interpreting globalization’s impact on borders. Instead of arguing that borders have become less important and more open because of globalization, he argues the opposite: that borders have become more important, and more difficult to cross—at least for some—because of globalization. Mau highlights the transformation borders have gone through from a static Westphalen understanding, via a ‘borderless’ perception, to the processual turn which meant borders began to be studied as dynamic, social processes rather than fixed points. In doing so, he echoes the current border studies discourse and, like others (e.g., Korte 2023; Shachar 2019), he maintains that fixed borders still play an active role in bordering and security. Chapter by chapter, he takes the reader through how passports, border walls, security, smart borders, and biometrics have fundamentally changed our borders and ways of controlling them.

For Mau, the key to understanding our current borders is to recognize that globalization is not about open or closed borders, it is about changing borders. He argues that in the globalized world, borders and security are not only performed at national borders, meaning they are not solely territorially fixed, rather, they are becoming more and more omnipresent with the advancement of smart borders. Still, he finds that territorial borders remain important as they act as points where people and travelers are willing to give up their information. That information helps enable flexible borders and is used in smart borders in exchange for a smoother border-crossing experience, which is always sought after by daily border crossers, businesses, and so on. There is a downside to this, however, as the smart border also widens the control beyond the physical border checkpoints, making it boundless yet still linked to the physical. As an example of extreme mobility control, Mau uses the case of China, a country where people can be denied buying a train ticket based on their moral behavior.

An interesting observation Mau makes is that he finds no apparent connection between political and economic systems and types of borders. Mau points out that liberal states, with liberal mindsets, do not always create liberal borders; instead, they try to balance between the right to exclude and the right to move. That being said, Mau does not see any difference between democratic and authoritarian states between rich and poor states when it comes to walled borders—they are found everywhere. Yet there is a trend of fortifying borders between the Global South and the Global North, which is reflected in the considerable differences in how easily citizens of democratic, authoritarian, rich, or poor states can cross the border. There is a red thread in the book concerning the increase in unequal treatment of different groups’ mobility, a development Mau links to globalization. He argues that borders have overwhelmingly been an advantage for the desired and privileged migrants. Those who either possess the skills or economic capabilities sought by other countries. This is perhaps the best and most obvious example of borders as sorting machines.

Mau uses risk assessment and a visa-wavering system to show how systems hinder mobility for the poor and the unwanted. In the case of the visa wavering system, it is especially noteworthy as it was initially intended to simplify border crossing for less fortunate people, but has developed into the exact opposite, and made it more difficult for them to cross while easing crossing for the rich. Border sorting machines not only help to maintain the status quo, but they also accelerate the gap between the mobile and nonmobile. When the wealthy can buy citizenships, so-called ‘Golden passports,’ mobility becomes a commodity; thus, the borders in the 21st century are selective because our solidarity is selective (Jäckels 2022).

While the book does not introduce groundbreaking findings regarding borders or mobility, its merit lies in Mau’s insightful observations and the elegant manner in which the book links and elucidates various bordering trends in a clear, accessible way, devoid of any insistence. It gives an excellent insight into how borders in the 21st century function and points out some areas that are increasingly becoming problematic—one being the de facto location of borders. As border control is no longer tied to territorial border checkpoints, it is increasingly pushed to other countries, sometimes far away, for example, the Nordic countries’ border begins in the Mediterranean, with great cost to local economic and environmental life (see also Chemlali 2023). Besides the violence, or perhaps in conjunction with it, the externalization and outsourcing of border control create a ‘legal vacuum, since many rights to protection can only be claimed after entry into a territory’ (p. 128). Mau also sees the opposite, that fluid borders are turned inward, creating societies with extreme (mobility) control. Like in China, where people can be denied simple mobility, for example, buying a domestic train ticket, based on their social behavior.

Although the book might not provide a deep and exhaustive historical context or comprehensive coverage of all aspects of contemporary borders, it remains engaging for both scholars and nonacademics alike. There are compelling reasons why individuals should delve into it, particularly as politicians and the media continue to debate the dichotomy between open and closed borders.