What are Boston New York and philadelphia referred as?

The cities of Boston, New York, and Philadelphia are sometimes collectively referred to as the "BosWash Megalopolis" or simply "BosWash." This term is used to describe the densely populated, economically connected region along the Northeastern seaboard of the United States that stretches from Boston, Massachusetts, to Washington, D.C. This urban corridor is characterized by a high concentration of cities, suburbs, and metropolitan areas and is an important center of culture, commerce, and innovation.