O’Neill focuses on the creation of flood control programs along the lower Mississippi River and the Sacramento River, the first two rivers to receive federal flood control aid. She describes how, in the early to mid-nineteenth century, planters, shippers, and merchants from both regions campaigned for federal assistance with flood control efforts. She explains how the federal government was slowly and reluctantly drawn into water management to the extent that, over time, nearly every river in the United States was reengineered. Her narrative culminates in the passage of the national Flood Control Act of 1936, which empowered the Army Corps of Engineers to build projects for all navigable rivers in conjunction with local authorities, effectively ending nationwide, comprehensive planning for the protection of water resources.