To assess the present condition of cities, Liberal Dreams and Nature's Limits focuses on five large North American cities at various times in the past - Philadelphia (about 1760), New York (1860), Chicago (1910), Los Angeles (1950), and Toronto (1975). Life inside these cities - specifically the economy, society and politics, public services, land development, and the geographies of circulation, workplaces, and residential districts - is the central concern of this book.

Another concern is drawing contrasts and similarities between the American and Canadian urban experiences.