Urban Field, a Geographical Definition
"A particular region can be considered an urban field when the constituent parts stretch over a territory larger than a single city and are still proximate enough to each other to suggest an "urban" density. More importantly, there should be strong signs of spatial deconcentration of residence, business and retail, as well as a moderate level of territorial specialization of functions, to such an extent that the field can be regarded as essentially polycentric, bearing witness to criss-cross relations in terms of the flow of people, commodities, money and information."
I arrived at this definition after reviewing the literature on urban fields. In most instances, urban fields are presented as a 'new' phenomenon, which is rather odd, considering that urban fields have been described and analysed for over a century. As with all 'new' phenemona, the theorists each seek to distinguish their view from the others by using new terms and different definitions. The terms are described in the glossary on this site. Here, I will draw from the definitions found in the literature to explain the definition cited above. It is imortant to note that the parameters used by theorists to define urban fields are rather 'geographical' in nature, while the real concerns are often more sociological. Therefore, it have called this definition a geographical definition. See my web article on this site for a more sociological analysis, which starts with this same definition.
Three characteristics come to mind most readily: proximity, density and size. Proximity of one urban area to the next. Proximity is both expressed on maps and felt on the ground level of streets and highways. Density is also considered important. For instance, a density of 500 inhabitants per square mile is the minimum for the “Megalopolis”. Though such measures are quite arbitrary and too much emphasis is given to the limits of the urban field, it is hard to call an area “urban” beyond certain levels of density. Size is similarly arbitrary but necessary. Where a 100 mile radius makes sense in most areas in the US, this measure is not applicable to the much smaller European areas that are often cited as examples. But surely, an urban field should exceed the size of a single city.
Proximity, density and size do not really account for the phenomenon. Therefore, characteristics such as deconcentration are more useful for a more precise definition. This refers to both to expansive suburbanization of residence and deconcentration of business – industrial, commercial, services – and retail.
In addition, it is often argued that new clusters of business, retail and residence take shape. Polycentricity occurs by way of deconcentration and of growing cities approaching each other. But whether the component “cores” are old or new, an urban field must contain more than one of them.
Many theorists suggest that specialization is a characteristic of urban fields. Certain economic and cultural functions are limited to certain areas, so that urban fields can be distinguished from regions where the center offers all specialized functions. It must be noted that such territorial specialization within urban field is far from complete.
To almost every urban theorist, what characterizes an urban field the most is the presence of criss-cross relations. Traffic increasingly flows from suburb to suburb, thereby supplementing and in part replacing center-periphery commuting. In addition, interrelations are expended through more fluid structures, such as economic and financial networks.
None of this is readily quantifiable. Indeed, depending on the rigor of the researcher, almost any heavily urbanized region in the western world can be made to fit the description. A definition is nonetheless useful to delineate urban field-like developments from the classical situation.