This study examines the forces that shaped the growth of western cities in antebellum America. The focus of the book is the rise and fall of St. Louis, the first major urban center of the trans-Mississippi region. During the mid-1840s St. Louis blossomed into a commercial giant and dominated the economic development of the Far West. Capital and migrants poured into the city, and it became a boomtown. Denied economic sustenance, rival trading centers withered and faded into obscurity. Cahokia, Kaskaskia, and Alton, for example, remained insignificant towns lost in a region controlled by the leading city of the Mississippi valley. Moreover, the growth of St. Louis shaped the economic development of the West, determining the flow of eastern capital and migrants to the area, the vitality of its trading partners, and the role of the region in the national economy.

The sources of St. Louis's vitality, however, have remained unknown. Scholars have not explained why St. Louis outdistanced its rivals and became the dominant city in the West. Nor have historians explained why the city failed to maintain its position as the commercial capital of the West. During the late 1850s Chicago supplanted St. Louis and became the leading city of the region, abruptly transforming the economic development of the region.