Tracing the birth of Denver and its sister cities Colorado Springs and Pueblo, Uniting Mountain and Plain recounts an important chapter in the transformation of the United States from a nation of traditional agricultural communities to a modern, urban, industrial society.

Standing at the intersection of the Rocky Mountains and the Great Plains, Denver shaped the regional economy that grew out of the discovery of gold in 1858. As Denver grew, Colorado Springs and Pueblo developed economic niches to complement the metropolis. Challenging the idea that front-range entrepreneurs acted as conduits for outside dollars, Kathleen Brosnan explores the sources of their capital and how they invested it across the region, showing how they remained independent of the outside economy for more than forty years. Market values influenced the region, but farmers, miners, state officials, and others created regulatory schemes and other quasi-legal systems to advance the interests of local communities vis-á-vis larger corporate interests.

By linking widely separated ecosystems in the urban-based economy of the Front Range, Brosnan notes, entrepreneurs created irrevocable environmental change and restructured the relations of the region's inhabitants with the land and with each other. Hispanic and Native American people who had lived in Colorado since long before the gold rush found themselves marginalized or displaced, foreshadowing the subsequent surrender of regional industries to the Goulds, Guggenheims, and Rockefellers by the early twentieth century.