Northeast megalopolis includes Portland.
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 . Portland, Oregon . It is in the Willamette Valley region of the Pacific Northwest , at the confluence of the Willamette and Columbia Rivers .