The term city region has been in use since about 1950 by urbanists, economists and urban planners to mean a metropolitan area and hinterland which has a shared and formal administrative government. Typically, it denotes a city, conurbation or urban zone with multiple administrative districts, but sharing resources like a central business district, labour market and transport network, such that it functions as a single unit.

In studying human geography, urban and regional planning or the regional dynamics of business it is often worthwhile having closer regard to dominant travel patterns during the working day (to the extent that these can be estimated and recorded), than to the rather arbitrary boundaries assigned to administrative bodies such as councils, prefectures, or to localities defined merely to optimise postal services. Inevitably City Regions change their shapes over time and quite reasonably politicians seek to redraw administrative boundary maps from time-to-time to keep in-tune with perceived geographic reality. The extent of a city region is usually proportional to the intensity of activity in and around its central business district, but the spacing of competing centres of population can also be highly influential. It will be apprciated that a city region need not have a symmetrical shape, and that is especially true in coastal or lakeside situations (consider for instance Oslo, Southampton or Chicago).