This article offers a longitudinal study of the complex entanglements between infrastructure and sovereignty in the Horn of Africa. By analysing Ethiopia’s imperial transport corridors, the political economy of Djibouti’s Red Sea ports, and the Greater Nile Oil Pipeline between South Sudan, Khartoum, and global markets, we underline the co-production of infrastructure and sovereignty as a defining feature of regional politics in the last 150 years. In a region notorious for the redrawing of borders, continuous violent conflict, and contested sovereignties, we emphasize the contingency of this relationship by making two central arguments. First, infrastructures have been central to the exercise of sovereignty and the consolidation of political orders in the region; dams, pipelines and ports have spearheaded efforts to hardwire centralizing political institutions, extractive commercial relations, and centripetal sentiments of belonging. Second, in doing so these infrastructures have sought to disable infrastructural alternatives because rival infrastructural visions embody competing claims of sovereignty. However, as state-building projects and the infrastructures they prioritize have often failed to successfully neutralise opposing articulations of political authority and belonging, we argue that the vulnerability of existing infrastructures contributes to the vulnerability of political order in the Horn. This article draws attention to the roads not taken and how those could have changed -and might still reconfigure-the politics of the region.