Megaregions of the United States

"Megaregion" is a term proposed by the Regional Plan Association (RPA), an American think-tank focused on urban planning. The megaregions of the United States, as the RPA defines them, are eleven regions of the United States that contain two or more roughly adjacent urban metropolitan areas that, through commonality of systems, including transportation, economies, resources, and ecologies, experience blurred boundaries between the urban centers, being perceived and acting as if they are a continuous urban area.

Source: Wikipedia — Megaregions of the United States (CC BY-SA 4.0)