The Northeast megalopolis (also Boston–Washington Corridor or Bos-Wash Corridor) is the most heavily urbanized region of the United States, running primarily northeast to southwest from the northern suburbs of Boston, Massachusetts, to the southern suburbs of Washington, D.C., in Northern Virginia. It includes the major cities of Boston, New York City, Philadelphia, Baltimore, and Washington, D.C., along with their metropolitan areas and suburbs as well as many smaller urban centers.