The U.S. economic development in the nineteenth century was characterized by the westward movement of population and the accumulation of productive land in the West. This paper presents a model of migration and land improvement to identify the quantitatively important forces driving this...

We develop a quantitative theory of mortality trends and population dynamics. We emphasize diseases as causes of death and individuals' decisions to reduce their mortality by adopting, at some cost, a modern health-related technology. Adoption confers a dynamic externality: Adoption becomes...