Abstract
William H. Dean, Jr. argued the development of a commercial agglomeration at any site is a function of three interrelated variables: trade routes, position, and nodality. Industrial agglomerations follow commercial ones. Dean's theory is discussed and applied to Chicago's growth before the Great Fire of 1871. The initial development of Chicago's transportation infrastructure is described. Data for the balance of receipts and shipments of selected items and growth rates for receipts and shipments from 1854 to 1871 are presented.