The BostWash corridor extends along the seaboard and inland, including five major metropolitan areas (Boston, New York, Baltimore, Philadelphia, and Washington), with numerous smaller urban areas with indistinct functional boundaries between them. Overlapping influences of large metropolitan areas, their interrelatedness, and their relationships with local, regional, and global processes characterize the urban corridor. With a population nearing 44 million, accounting for about 17% of the U.S. population, but occupying only 2% of its landmass, the significance of the corridor as a sphere of consumption is indisputable. The New York metropolitan area alone, with its population of 21.2 million, accounts for 7.5% of the national population. High population densities, over 250 persons per square mile, on a conterminous segment of about 400 miles between Boston and Washington are also observed.