This article examines the evolution of mill districts in Shanghai and Mumbai across the 20th century as cases of political heritage—in which the socio-spatial formations of factory and neighbourhood produced new meanings of citizenship for the workers in each city. Using historical materials from the textile industry in each city, government reports, housing data, and secondary sources, this article first traces the origins of Shanghai’s textile industry in the 19th century to its connections with Bombay’s textile mills, then examines the emergence of working-class neighbourhoods as they acquired distinctive patterns of tenement housing, shopfronts, and street life. The main finding is that despite clear differences in the two cities in terms of religion, culture, and politics, the ‘mill district’ became a socio-cultural formation central to the identity and memory of generations of textile workers in Shanghai and Mumbai. A concluding section examines the similar process in each city in the 21st century in which mill compounds and neighbourhoods were converted into high-end commercial real estate and sites for consumption and leisure.