Global trends in urbanization raise questions about how cities are defined. An analysis of 228 countries and areas of the world by the United Nations shows that governments use different definitions, underscoring the degree to which the concept is contested, and pointing to the difficulties of gathering data in a field without standard definitions:
- 105 countries base their city data on administrative criteria, usually geographic boundaries such as “city limits” (83 use this as their sole method of distinguishing urban from rural).
- 100 countries define cities by population size or population density (57 use this as their sole urban criterion). However, the minimum population deemed necessary to constitute a city ranges broadly, from a low of 200 to a high of 50,000.
- 25 countries specify economic characteristics as significant, though not exclusive, in defining cities - typically, the proportion of the labour force employed in non-agricultural activities.
- 18 countries count the availability of urban infrastructure in their definitions, including the presence of paved streets, water supply systems, sewage systems or electric lighting (United Nations, 1998 & 2004).
Interestingly, 25 countries provide no definition of “urban” at all, whereas six countries regard their entire populations as urban (United Nations, 1998 & 2004).
While “city” and “urban” are often used interchangeably, they can denote different concepts. Though “city” normally refers to the statistical grouping of people in a single area, “urban” can refer to the transformation in mindset that occurs in cities. “Urban” generally denotes the altered patterns of social, economic, political and cultural interaction unique to cities that develop as a result of different kinds of employment, diversified social and political structures, and the built environment, among other factors. The 1938 characterization of “urban as a way life” by Louis Wirth continues to inform the study of the modern city and urbanization trends worldwide