Market-mediated imperial growth: territorial purchase and the political economy of sovereignty

Why do states sometimes purchase territory rather than acquire it through conquest? Despite numerous historical cases in which sovereignty changed hands through formal sale including the Louisiana Purchase, the Alaska Purchase and the 1898 Treaty of Paris, territorial purchase remains undertheorised in international relations scholarship. This article develops a political economy theory of territorial purchase, arguing that market-like territorial transactions emerge under specific configurations of power asymmetry, normative environment and systemic constraint. Drawing on theories of international hierarchy, constructivist scholarship on sovereignty norms and the economic statecraft literature, I argue that purchase becomes attractive when an aspiring power possesses substantial fiscal capacity but faces geopolitical, normative, or domestic constraints on the use of force. The article identifies two causal variants, substitutive purchase, in which capital replaces coercion, and ratifying purchase, in which capital legalises it. It develops the first through process tracing of three core cases. The findings demonstrate that imperial growth is not reducible to conquest alone, and that sovereignty has historically functioned as an alienable bundle of rights whose transferability was shaped by specific normative conditions.