My dissertation focuses on the tandem twentieth-century developments of Panamanian state formation and U.S. empire building on the Isthmus of Panama, a transit space of global importance. Specifically, I chart attempts through the first half of the twentieth century to domesticate and control this space by focusing on the construction and maintenance of borders, both imperial (e.g. the Canal Zone border) and national (e.g. those that guarded Panamanian sovereignty). These regulatory systems will be explored through interactions between the states’ functionaries, the people of Panama, and the Isthmus’s growing diasporic cultures in relation to smuggling and other transnational illegal “flows” passing across the Isthmus. Such “flows” include peoples, arms, contraband, gems, drugs, and exiles. There are three interrelated conceptual areas of my project. The first, U.S. imperialism, examines the neglected relationship between the criminalization of certain goods and activities and political and economic domination. My research charts parallel developments: the “Americanization” of the Panamanian criminal justice system on the one hand and the myriad imperial policies that led to conditions in the republic favorable to increasingly lucrative illegal activity on the other. The second focus, Panamanian state formation, centers on the interwoven nature of illegal activity in Panamanian state formation. My project seeks to broaden the traditional definition of what constitutes a state strategy to secure revenue, exploring the ways the state “unofficially” engaged lucrative illegal activity as another form of institutionalized state politics and power. Last, I focus on illicit traders, those who operated from the perspective that a state border was less a legitimate claim to controlling territory and more an obstacle between the movement of goods and profit. My study charts the ways in which diverse traders complicated, contested, and participated in these state forms of domestication and control through illegal regional trade. This dance - between those constructing and guarding the Isthmus’s multiple boundaries and those attempting to subvert them - highlights the dynamic interactions of a state in formation, a budding empire, and the vast illegal economic activity that developed alongside legal trade.