As of 2010, there were 4,231 cities with 100,000 or more people. To better understand them, the Monitoring Urban Expansion initiative tracked a stratified global sample of 200—collecting and analyzing the evidence on the quantity of land required for urban expansion, on its physical organization and affordability, and on the forces affecting it.
Monitoring Urban Expansion consists of four phases of mission-driven research.
Phase I focuses on mapping and measuring global urban expansion in the sample of cities from 1990 to 2014, using Landsat satellite imagery.
Phase II focuses on mapping and measuring urban layouts in the sample, using high-resolution satellite imagery.
Phase III involves a land and housing survey that focuses on regulatory regimes and affordability.
Phase IV will involve mapping and estimating urban extent in the entire universe of cities out to 2045.
This initiative was a partnership with the United Nations Human Settlements Programme (UN-Habitat) and the Lincoln Institute of Land Policy, and it served as the foundation for the Atlas of Urban Expansion.
Following the global Atlas, several additional regional and national analyses have generated valuable information on urban expansion. As a result, we have updated urban extents and metrics for more than 200 cities that weren’t included in the global Atlas.