Planning for Megaregions in the united states

The population of the United States will likely grow by 40 percent by 2050 with the growth concentrated in eight to ten megaregions, connected networks of metropolitan areas. Planners in the United States have begun to plan for these large regions. Their work raises four persistent questions: what is a megaregion, and how does one determine where a megaregion exists? Why plan at the scale of megaregions rather than at metropolitan, state, and national levels? What are appropriate methods and useful data for megaregion planning? When is the rnegaregion a useful scale for policy and planning?