especially chimpanzees, into the human population at some point in the 19th or
early 20th century in that part of Africa. Medical geographers have also been able
to sometimes track the spatial movement of the disease within specific countries,
leading to strategies on how to slow or stop the spread of the virus. For example,
in Tanzania in the early 1990s it was discovered that the incidence of HIV infec-
tion dropped significantly as distance from a major roadway increased. This spa-
tial distribution led health care officials to theorize that long-haul truck drivers,
frequent customers of the country’s sex workers, were primary agents of spreading
the disease along transportation routes, especially roads. Truck drivers therefore
have become an important group targeted by government educational programs,
designed to combat the spread of AIDS by promoting the use of condoms and
limiting high-risk sexual behavior.
Megalopolis
A term from urban geography that identifies a large, contiguous urban region. The
word was first used by the French geographer Jean Gottman in describing the strip
ofurbanizationrunning along the eastern seaboard of the United States from Bos-
ton, Massachusetts, to Washington, D.C. Another term for this concentrated zone of
urban development is BosWash, an amalgamation of the names of the terminal
cities. The label of “megalopolis” is now applied to any large urban conurbation
anywhere in the world, and many such locations may be identified. Typically, a
megalopolis is characterized by a largepopulation, dense and sophisticated trans-
portation systems, a concentration of industrial and service economic functions,
and numerous urban problems, such as higher levels of pollution, greater conges-
tion, and loss of green space. A 2005 study by Robert Lang and Dawn Dhavale iden-
tified 10 “megapolitan areas” in the United States. To qualify for this label, an urban
corridor had to include a combined population of at least 10 million by the year
2040, occupy a similar physical geography, represent an identifiable cultural region
with a common sense of identity, and be “linked by major transportation infrastruc-
ture,” among other criteria. Lang and Dhavale identified 10 such urban regions
within the United States, and highlighted the economic, demographic, and political
power such mega-cities represent. According to their study, approximately two-
thirds of the U.S. population lives within theboundariesof a megapolitan area,
and 80 percent of the members of the U.S. House of Representatives have some
portion of their congressional district lying within such a region.
Thetoponymyof the 10 areas delineated by the research of Lang and Dhavale
reveals both thelocationand identity of the megalopolis. The “I-35 Corridor,” for
Megalopolis 223