In our era of climate change, littoral and low-lying cities face tremendous and increasingly unpredictable environmental hazards. The long-term coastalization of the world population,Footnote ¹ in good part a product of the first globalization period explored in this special issue, has entailed that the Atlantic, Indian and Pacific rims are now home to 37 per cent of the global population and many of the world’s fastest-growing megacities.Footnote ² Cities such as Calcutta or Lagos, but also the smaller cities studied in this special issue, were both products and drivers of this long-term coastalization, fuelled by colonialism, imperialism and capitalism. In adding historical depth to these processes, the special issue addresses pressing present-day concerns.

Lest this special issue thus be accused of presentism, a charge that urban historians often level at their less historically inclined colleagues,Footnote ³ we hasten to add that as editors we initially saw this supplement as an experiment on how global urban history could and should be written. When we devised two workshops in Berlin as a part of the Patchwork Cities project financed by the Swiss National Science Foundation, our goals were twofold. As the introduction to this issue by Christian Jones and Yorim Spoelder underlines, the first purpose was to bring together scholars working on the social histories of port cities in the world’s commodity exporting regions, most of them colonial or semi-colonial in the late nineteenth and early twentieth centuries. The rationale was thus to connect the thriving historiographies of cities in disparate world regions, which until the last decade’s various initiatives surrounding global urban history have too often been divided into their respective historical area studies. This combination should help to identify cross-regional themes and similarities in urban history that may previously have been masked by the institutional distance that separates historians of, say, Buenos Aires from those of Singapore – in spite of such cities’ remarkable functional similarities from the angle of global history.

For at least two decades, global historians have produced a burgeoning literature on port cities, delineating their function in global connectivity.Footnote ⁴ Building on this groundwork, our second purpose was to zoom into the fine-grained social histories of such cities and bring their local dynamics back into focus. The aim was to bring to bear some of urban history’s micro-historical sensibilities on larger discussions in global, and especially in colonial, history. Colombo, Lagos or Iquitos, from this angle, come to look like products and receptacles, but also like laboratories and promoters of a longue durée urban history, in which the global dominance of European and North American urbanization at the turn of the twentieth century has long since faded. Specific forms of ethnicized and racialized socio-economic inequalities, and segregation in particular, have come to form a key interest in this research agenda.Footnote ⁵

The eventual outcome, in turn, focused much more on environmental questions than the erstwhile plan. At the workshops, we noticed that many contributions delved into interactions between the natural, built and social landscapes in port cities. In particular, questions of water management or waste disposal were present in reflections on the social histories of places as far apart as Iquitos, Port Said and Colombo. Since none of the four editors and only a few of the contributors entered our conversations with fully fledged environmentalist predilections, the degree to which they flooded our research agenda raises follow-up questions: Is this a side effect of the choice of particular kinds of cities? Is it a feature of their locations, which Europeans, who produced a disproportionate share of the primary sources on which the articles rest, considered especially environmentally hazardous? How much of the environmental focus stems from adopting a particular temporal lens that focuses on these cities’ early histories, when locations for settlement were discussed under an explicitly environmental angle, or when much of the urban fabric was still precarious and highly unstable? Urban historians at large will hardly be taken aback that flooding, garbage and public health occupied the minds of planners, municipalities and colonial officials. But did such issues play a greater role in engraving socio-economic inequalities into the fabrics of our cities than they did in Liverpool or Antwerp?

Albeit partly the product of an editorial choice to embrace our socio-environmental focus, the contributions collected in this volume nonetheless reveal its relevance in the longue durée. Cumulatively, the contributions show the long arch from the foundation to the ending of port cities outside the North Atlantic. Environmental considerations most obviously underpinned the inter-imperial rivalries that shaped the early history of Sandakan in North Borneo, examined by Michael Yeo. But they equally informed the urban interventions, likewise underwritten by inter-imperial themes, that transformed Beirut from a seaport into an airport hub in the mid-twentieth century, as Cyrus Schayegh shows. Adrián Lerner Patrón’s longue durée example of Iquitos, but also Olivia Durand’s comparative study of Odessa and New Orleans, both provide cautionary tales against treating ‘the environment’ as a stable and unchanging canvas upon which cityscapes can be drawn according to planners’ whims.

As many of the cities in this special issue experienced vertiginous growth in the late nineteenth and early twentieth centuries – or were founded anew, like Port Said – historians should not treat their social histories as a question of the distribution of resources over a given space. Longue durée biographies of cities may have gone out of fashion in urban history. Yet, as many of our contributions show, they do have the virtue of revealing that social, ethnic and racial inequalities were deeply embedded in environmental path dependencies. Ademide Adelusi-Adeluyi, for instance, demonstrates how Lagos’ division into Yoruba, Brazilian and European quarters interacted with differential attitudes and practices of water management. In nineteenth-century Colombo, too, Sujit Sivasundaram writes, ‘The segmentation of peoples and nature’ fuelled ‘the rise of inter-human conflict along lines of class as well as ethnicity and livelihood.’ Erosion, flooding and storms were never far from struggles over how spatially to apportion the cosmopolitanism of New Orleans and Odessa. The most hazardous and precarious part of Iquitos, Belén, sometimes called ‘the Venice of the poor’ on account of floating or being built on stilts into the whimsical river, was initially an indigenous pier and hamlet. Waste disposal and garbage collection were profoundly ethnicized in late nineteenth-century Port Said, as Lucia Carminati stresses. In Calcutta, according to Anindita Ghosh’s contribution, caste interacted with scavenging. The conflagration of deep-seated racism and Hurricane Katrina in 2005, though outside of Olivia Durand’s temporal purview, spotlighted that such themes have lost none of their urgency in our age.

Extolling the longue durée and stressing path dependencies, to be sure, is not the same as asserting that all was set in stone from the get-go. Some changes owed much to the instability of the natural environment itself, as in Adrián Lerner Patrón’s example of the changing course of the Amazon River. But the long-term perspective cumulatively emerging from this special issue also makes room for over-determined layers of urban change. Beirut’s emergence as the Middle East’s foremost airport hub brought about consequential social as well as environmental transformations within the city, but also across the broader region. Yet, as Cyrus Schayegh’s article shows, these were over-determined by its previous role as a seaport, by its multi-ethnic character and reputation, by diasporic connections, as well as by the intersection of various imperial interests. Planning interventions, infrastructure projects and social engineering had to cope with the existing urban fabric, which itself arose from the intertwining of natural and built environments.

Adopting this special issue’s twin focus on social inequalities and the environment ultimately yields wider historiographic implications. It amounts to a plea for a ‘history…that focuses on the people, their city and environment’, as Ademide Adelusi-Adeluyi puts it when lamenting the near-absence of such a history for the case of West Africa. The combination nearly unavoidably entails that certain expectable features or actors, on the environmental as well as on the social and urban side, receive less attention. The focus on port cities, for example, will foreground water over soils, forestry and air. This may in turn ease communication with the broader field of global history and its trademark metaphors of liquidity, even as our title term of ‘breakwaters’ and our attention to inequalities gesture to the growing tendency among global historians to consider disconnections. Conversely, some of the classic protagonists of port city histories, such as dockworkers, sailors, merchants and financiers, will recede into the background. Spatial segregation, though often considered a central feature of multi-ethnic colonial (and semi-colonial) cities, instead comes to look more enmeshed with environmental issues than has been customary.Footnote ⁶

From an even more long-term perspective of global urban history, the period from the mid-nineteenth to the mid-twentieth century, on which many of our contributions concentrate, stands out as the apogee of North Atlantic urbanization. Although this moment profoundly and lastingly shaped urban theories and the thought habits of urban history as a distinct field, it looks far more ephemeral from today’s angle than it did to Max Weber or Louis Wirth. Our choice to study port cities in the Global South during this Eurocentric historical moment, of which our cities of course were partial products, offers broader lessons. Kernels or harbingers of global urbanization patterns in the twentieth century, their study recommends adopting a long-term socio-environmental lens that may well be less obtrusively urgent in research about cities such as nineteenth-century Paris. It must combine simultaneous attention to natural and built environments as well as the making of social space with a longue durée sensitivity.