Editing Urban structure (section)

==Multiple nuclei model==

{{main|Multiple nuclei model}}

Geographers [[Chauncy Harris]] and [[Edward Ullman]] developed the multiple nuclei model in 1945.<ref>Harris C D and Ullman E L (1945), "The nature of cities" Annals of the American Academy of Political and Social Science 242: 7-17</ref>  According to this model, a city contains more than one center around which activities revolve.  Some activities are attracted to particular nodes while others try to avoid them. For example, a university node may attract well-educated residents, pizzerias, and bookstores, whereas an airport may attract hotels and warehouses. Other businesses may also form clusters, sometimes known locally as [[wikt:iron triangle|Iron Triangle]]s for automobile repair or [[red light district]]s for prostitution, or [[arts district]]s. Incompatible activities will avoid clustering in the same area, explaining why heavy industry and high-income housing rarely exist in the same neighbourhood.