"Catchment area (human geography)

In human geography: a catchment area is the area and population from which a city or individual service attracts visitors or customers. ... Catchment areas are generally founded either on formal local government boundaries or else on some other geographic basis. For example, a neighbourhood or district of a city often has several small convenience shops, each with a catchment area of several streets. Supermarkets, on the other hand, have a much lower density, with catchment areas of several neighbourhoods (or several villages in rural areas). This principle, similar to the Central Place Theory, makes catchment areas an important area of study for geographers, economists, and urban planners."