In the study of human settlements, an
agglomeration is an extended
city or
town area comprising the built-up area of a central place (
usually a municipality) and any
suburbs linked by continuous
urban area. In France,
INSEE the French Statistical Institute, translate it as "
Unité urbaine" which means continuous urbanized area. However, because of differences in definitions of what does and does not constitute an "agglomeration", as well as variations and limitations in statistical or geographical methodology, it can be problematic to compare different agglomerations around the world. It may not be clear, for instance, whether an area should be considered to be a satellite and part of an agglomeration, or a distinct entity in itself.
The term "agglomeration" can also be linked to "Conurbation," which is a more specific term for large urban clusters where the built-up zones of influence of distinct cities or towns are connected by continuous built-up development (Essen - Dortmund and others in the Rhine-Ruhr district), even in different regions, states or countries, Lille - Kortrijk in France and Belgium). Each city or town in a conurbation may nevertheless continue to act as an independent focus for a substantial part of the area.
A metropolitan area may be defined as an extended agglomeration or conurbation that also includes peripheral areas not themselves necessarily urban in character but closely bound to the urban area by flows linked to employment or commerce. The population may easily travel within an agglomeration by car or mass transit system. For example if one lives a 30-minute rail trip away from downtown New York City, yet in a separately-named smaller county or state outside the city limits, that district or town would be considered a part of the New York agglomeration.
The agglomeration can also consist of legal administrative divisions where data is easily available because coming from one administrative level (Metro Area, City, Town, County, ...) The Greater Tokyo Area provides an example of the difficulties involved because estimates of its population vary according to how it is defined. While the prefectures of Tokyo, Chiba, Kanagawa and Saitama are commonly used to define Greater Tokyo, the Japan Statistics Bureau simply measures the area within 50 kilometers of the Tokyo Metropolitan Government Offices in Shinjuku[1] [2].
