The era of ‘imperial globalization’ at the turn of the twentieth century was also the age of colonial railways. The global network of railway lines has never expanded faster than in the decades before and after 1900. Regarded as terrestrial extensions of marine networks, colonial railways are usually embedded in a history of global integration. Focusing on the case study of the Uganda Railway in present-day Kenya and based on a wide array of primary sources and interviews, the dissertation refines this picture by moving away from a pure macro perspective towards examining the impact of the railway line on specific places and communities in East Africa. The Uganda Railway, built by the British between 1896 and 1901 to connect Uganda with the Indian Ocean, was an engine of rapid and fundamental change even beyond the territories it crossed. As a relational system, the railway line did not have a uniform effect, but led to a plethora of consequences depending on context, location, and actors. Informed by theories and debates in global history, infrastructure studies, and the history of space, the dissertation asks how the railway transformed social and spatial relations in East Africa from the onset of colonial conquest to the First World War, arguing that from the perspective of specific localities the railway was not a medium of integration. Instead, it distorted and disintegrated social, political, and economic relations and established a regime of fragmentation. By telling the story of the division of Maasailand, the deforestation of central Kenya, the emergence of migratory labour, the birth of Nairobi, and the consequences of Nandi resistance, the thesis not only rewrites the common history of the Uganda Railway, but also illuminates the unintended and often neglected consequences of imperial infrastructure that affected the configurations of daily life in East Africa. The thesis thus provides a nuanced understanding of the impact of infrastructures and the techniques of colonialism at a time when all over Africa railway lines heralded the age of high imperialism.