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The Evolution of Urban Structure:

central cities: the original, core jurisdictions of metropolitan areas.

isochron: a line connecting points of similar time (distance traveled in a given time) determining the radius of the city.
Innovations in transportation extend the isochron of commuting distance - thus allowing the city to sprawl.

Temporal Urban Mapping (mirror site in France)- Animation of urban growth for the San Francisco Bay Area and of Washington DC

sprawl: a term, often used pejoratively, describing the unplanned extension of relatively low-density urban land uses into rural areas, usually alongside main roads. Sprawl implies little control of land subdivision, so that the conversion of plots for urban uses may create enclaves of agricultural land . . . (RJ. Johnston Dictionary of Human Geography Blackwell Press 2000).

edge cities: nodal concentrations of shopping and office space that are situated on the outer fringes of metropolitan areas, typically near major highway intersections.


fiscal squeeze: increasing limitations on city revenues, combined with increasing demands for expenditure.

hinterland: the sphere of economic influence of a city or town. The resource area of a city.


Social and ethnic clustering/social ecology - people congregate or discriminate resulting in segregation.

minority groups: population subgroups that are seen, or that see themselves, as somehow different from the general population.

congregation: the territorial and residential clustering of specific groups or subgroups of people.

redlining: the practice whereby lending institutions delimit "bad risk" neighborhoods on a city map and then use the map as the basis for determining loans.

segregation: the spatial separation of specific population subgroups within a wider population.

central business district (CBD): central nucleus of commercial land uses in a city.

zone in transition: area of mixed commercial and residential uses surrounding the CBD.

invasion and succession: a process of neighborhood change whereby one social or ethnic group succeeds another.

gentrification: the invasion of older, centrally located working-class neighborhoods by higher-income households seeking the character and convenience of less expensive and well-located residences.


Additional Resources:

Urban Geography