Resource and land frontiers have always been a significant focus of geography but have become overlooked in economics and economic history. Yet a critical driving force behind global economic development has been the response of human society to natural resource scarcity, not just through conserving scarce resources but also by obtaining and developing more of them. A handful of theories of how such classic frontier expansion has shaped economic development have been formulated, and these are discussed and reviewed. Evidence from history is cited to illustrate these effects, and the implications for resource-based development in the Contemporary Era (1950 to present) are discussed. Unlike previous eras, the pattern of frontier expansion is dualistic. This has led to less economy-wide benefits from frontier-based development in the Contemporary Era.