This term has been in use since about 1950 by urbanists, economists and land-use planners to mean not just the administrative area of a recognisable city or conurbation but also its hinterland that will often be far bigger. Conventionally, if one lives in an apparently rural area, suburb or county town where a majority of wage-earners travel into a particular city for a full or part-time job then one is (in effect) residing in the city region, even though one would not admit this to friends!

In studying human geography 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 influencial. 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).

See also gerrymander, commuter, garden city