Atlantic Seaboard Conurbation at Night, United States of America
Note: This caption refers to the image versions labeled "NASA's Earth Observatory web site".
As regional metropolitan areas expand in both physical area and population, they typically aggregate to form economically, politically, and to some extent socially linked entities known as conurbations - the term "megalopolis" has also been used. One of the largest conurbations in the world is located along the eastern coastline of the United States, and has been termed the Atlantic Seaboard Conurbation (ASC). The ASC extends over 1000 kilometers and includes the major economic, governmental, and cultural centers of Boston, MA; New York, NY; Philadelphia, PA; Baltimore, MD; and Washington, D.C.
This astronaut photograph includes every metropolitan area in the ASC except for Boston, MA (located off the image to the northeast of New York, NY). The image was taken during local night, which highlights the position and extent of each metropolitan area along the eastern seaboard by their urban lighting patterns. The establishment and growth of the conurbation was facilitated by transportation networks (railroads, highways, and air travel routes) for transfer of goods, materials, and population between the metropolitan areas.
Two other large metropolitan areas are visible in the image - Norfolk, VA and Richmond, VA at image lower left - but these are not considered to be part of the ASC. In contrast to the city lights that mark metropolitan areas and smaller communities along the sea coast and interior, the Atlantic Ocean appears as a featureless dark region occupying the lower right quarter of the image.