The document discusses California's development of infrastructure in the 20th century to support its growing population. It focuses on California's water projects, which were crucial because much of the state is desert. In the late 19th century, Engineer William Hammond Hall researched water projects and established a framework for irrigation districts. Major dams, aqueducts and reservoirs were then built in the 20th century to bring water from distant sources like the Colorado River to the arid Central Valley and southern regions, transforming agriculture. These massive water projects took significant investment, technology, effort and coordination but were critical to enabling California's growth into a mega-state.