With the 2020 United States Census going on this year, eyes are being turned to data defining who we are, where we live, and what we do. Just as there are myriads of ways to conduct our lives, there are plenty of places we can choose to live as well. In early March of 2020, the UN Statistical Commission unveiled their endorsement for a new way of both defining and classifying cities.
A city seems like it would be pretty easy to define, and yet every country has a different way to determine what is a city and what isn’t. Factors that are used often include population, services and infrastructure, and administrative declaration.
Defining Cities, Towns, and Rural Areas Based on GIS Data and Satellite Imagery
The UN Statistical Commission used information gathered from multiple international organizations (including UN-Habitat, World Bank, ILO, FAO, and OECD) to endorse the Degree of Urbanization model of classifying urban and rural areas. This model utilizes data gathered through open satellite imagery and global spatial information.
The Degree of Urbanization classifies urban, semi-urban, and rural areas in the following manner:
- Cities are defined as locations with at least 50,000 inhabitants who live in contiguous grid cells, with over 1,500 people per kilometer squared;
- Semi-dense or town areas are defined as places with populations of 5,000 people or more, with 300 or more inhabitants living in a kilometer squared space;
- And rural areas, with populations living in low density grid cells.
The Degree of Urbanization allows for aggregate data to be researched. For instance, access to water can be looked at, as urban or more populated areas most often are built around naturally water rich locations. Additionally, infrastructure and public services are most likely to be found in urban areas, and these services can be more expensive in larger cities than they are in rural areas. However, the average income can also be looked at through the urban/rural divide.
The research backing the Degree of Urbanization model hinged upon the ability to gain international agreement for this method. The Degree of Urbanization method took the most used factors for urbanization, population and density, and used those as the basis for gaining the most accurate data worldwide.
The Degree of Urbanization method can be used to more accurately determine the comparison and implementation of the UN’s Sustainable Development Goals. By defining urban and rural areas, these goals can be looked at through the appropriate data to see where they have been achieved and where there is more work to be done.
Kemper, Thomas. Building a new global definition of cities – from space. 19 March 2020. Retrieved from http://www.earthobservations.org/geo_blog_obs.php?id=416