The presence of a westward-moving frontier of settlement shaped early U.S. history. In 1893, the his-torian Frederick Jackson Turner famously argued that the American frontier fostered individualism.We investigate the Frontier Thesis and identify its long-run implications for culture and politics. Wetrack the frontier throughout the 1790–1890 period and construct a novel, county-level measure of to-tal frontier experience (TFE). Historically, frontier locations had distinctive demographics and greaterindividualism. Long after the closing of the frontier, counties with greater TFE exhibit more pervasiveindividualism and opposition to redistribution. This pattern cuts across known divides in the U.S.,including urban–rural and north–south. We provide evidence on the roots of frontier culture, identi-fying both selective migration and a causal effect of frontier exposure on individualism. Overall, ourfindings shed new light on the frontier’s persistent legacy of rugged individualism.