The opening decades of the twentieth century were a period of great change in international politics. The First World War led not only to a reallocation of territorial possessions—the empires of the great powers had reached their zeniths—but also to a reallocation of power in world politics. Leadership began to flow from Great Britain, the “weary titan,” to the comparatively wealthy and vibrant United States. The newly formed League of Nations sought to manage international conflict but, with the United States refusing to join, was soon overwhelmed by rising violence. Nations turned inward, no longer willing to pursue the economic interdependence of the late nineteenth century. In E. H. Carr’s famous words, a “twenty years’ crisis” began at the close of the “war to end all wars”; the crisis culminated in the onset of another, even deadlier, war in 1939. These were also decades of ferment at home. The Progressive movement was recasting American politics, while the voting franchise expanded. At the same time the federal government was becoming a much more significant force in American life. The role of the federal government had long been limited. What scholars call the administrative state was quite small until the early twentieth century. By the 1940s, by contrast, the federal government comprised a rich and powerful array of agencies and departments, many devoted to regulating economic and social relations. These regulatory agencies, and the laws they implemented, provided a new frontier in the development of norms and rules of territoriality. The onset of comprehensive national regulation had many causes. Industrialization, the nationalization of the economy, and the Depression and its associated political upheaval—all these and more contributed to a remarkable shift in the role of government. In a wave of lawmaking that began in the 1890s, and accelerated dramatically with the New Deal, the United States promulgated a myriad of new laws aimed at subjecting economic and social activity to government power. One of the first examples of this new genre of statutes was the Sherman Anti-Trust Act of 1890.