On October 20th, 1877, the English editor of The Rising Sun and Nagasaki Express bemoaned the state of foreign residents in the Japanese treaty port of Nagasaki, claiming that “like uncared-for and straying sheep” they were neglected by Japanese authorities who were allowing the settlement to fall to ruin. Complaints were common enough in newspapers across the world in the nineteenth century, but these claims are striking because at the same time the editor was publishing this issue, the influence of European and American treaty powers was in the ascendance in East Asia. In the second half of the nineteenth century, designated treaty port cities, opened to European and American trade through a series of unequal treaties, proliferated across the coastlines of China, Korea, and Japan. These port cities are often categorized as “semi-colonial,” a mixture of treaty-enforced colonial hierarchies and local administrative control. This dissertation uses the space of the city of Nagasaki to explore what happens when European and American residents did not have the economic or political capital to enforce treaty privileges. Compared to more famous treaty ports like Shanghai or Yokohama, Nagasaki’s small foreign community could do little to capitalize on the colonial structures created by the unequal treaties. This opened up space for the Japanese residents of the city to become the drivers of its modernization and urban development. It was a place where Euro-American imperialism met the rising strength of the Japanese empire on Japanese land, and alliances within the port were as likely to be made across imperial boundaries as within them. Through a series of case studies focusing on the transnational enterprises of trade, intimate relationships, education, and entertainment, this dissertation shows how the geographies of the transnational landscapes aided or hindered Nagasaki residents who attempted to partake in them. By bridging conversations in post-colonial studies, treaty port studies, and modern Japanese history, this dissertation examines the social and physical networks of Nagasaki to demonstrate a new way of understanding treaty ports not as cleanly bifurcated colonial spaces, but as the sites of complex and layered transnational landscapes. Identity categories like race, gender, nationality, and class mapped differently across different landscapes, at times in unexpected ways. In these transnational landscapes, Nagasaki was both frontier and homeland, where the local could and did compete with larger national and international systems.