Megaregions can help the United States contend with its mega-challenges. With shared economies, natural resource systems, infrastructure, history, and culture, these linked networks of metropolitan areas and their hinterlands-such as the Southwestern Sun Corridor or Great Lakes-can strengthen climate resilience, natural resource management, economic competitiveness, and equity at the local, regional, and national levels in the United States. This source book provides updated demographic, economic, and environmental information on U.S. megaregions for urban and regional planners, policy makers, academics, and decision makers in transportation, environmental protection, and development agencies. The book reviews the origins of the megaregion concept and the economic, ecological, demographic, and political dynamics. Readers will understand trends, processes, and innovative practices within and between megaregions and identify the most pressing challenges that demand strategic decisions and actions.