Defining and Measuring Urbanization

There is no single, universally agreed definition of what makes a settlement "urban." Countries apply wildly different criteria, which makes global comparisons trickier than they first appear. Denmark counts any cluster of at least 200 inhabitants with less than 200 meters between buildings as urban. Japan requires a municipality of at least 50,000 people with roughly 60% of its land in urban use. The United States Census Bureau relies on housing-unit density and contiguous built-up area rather than a simple population cutoff, and it revised its methodology in the 2020 census to tighten density thresholds. China, meanwhile, distinguishes urban from rural largely through the hukou household-registration system, an administrative status that does not always match the physical built environment on the ground. The United Nations Demographic Yearbook compiles these national definitions rather than imposing one of its own, which means that "percentage urban" figures reported for different countries are not strictly comparable.