THE U.S. WESTWARD EXPANSION.

The U.S. economic development in the 19th century was characterized by the westward movement of population and the accumulation of productive land in the West. This article presents a model of migration and land improvement to identify the quantitatively important forces driving these phenomena. The conclusion is that the decrease in transportation costs induced the westward migration, whereas population growth was responsible for the investment in productive land. [ABSTRACT FROM AUTHOR]