First published in 1951, The Great Frontier has become one of the undisputed classics of Western history, its conclusions still hotly debated by scholars but nonetheless essential and engrossing reading for anyone who wishes to understand the history and significance of this vast and often puzzling region. The final work of pioneer Western historian Walter Prescott Webb, The Great Frontier represents a daring attempt to interpret the settlement of the American West in the global context of the expansion of European civilization between the fifteenth and twentieth centuries. According to Webb's "boom hypothesis," the expansion of Europe's "Great Frontier" into the Western Hemisphere energized a static society and made possible the development of such fundamental institutions of the modern era as individualism capitalism, and political democracy. Webb contends that the closing of the global frontier at the end of the nineteenth century, with the end of easily available empty land and readily exploited natural resources, was responsible for the crises and violence of the twentieth century and boded ill for the future of the United States's treasured democracy. An insightful new introduction by Western historian William D. Rowley sets Webb's masterwork into the context of its own time and outlines the relevance of this still-controversial work for twenty-first-century readers.