Before the publication of Nature's Metropolis in 1991, historians generally treated urban and rural areas as distinct from one another, each following separate lines of development and maturity. Using Chicago and its surrounding areas as a model, Cronon shows that the city-country story should be treated as a unified narrative, with each part inseparable from, and dependent on, the other. Cronon builds on Frederick Jackson Turner's nineteenth century "frontier thesis," which stressed the effect that taming the wilderness had on the American character. He argues that nature has shaped human creativity and that capitalist market forces played the major role in changing urban and rural areas together.