Urban Area
A densely settled geographic area defined by the Census Bureau based on population density thresholds, used to classify territory as urban or rural.
The Census Bureau defines urban areas using population density criteria applied to Census blocks and tracts. For the 2020 Census, the Bureau revised its methodology: an urban area must contain at least 2,000 housing units or 5,000 people, with qualifying Census blocks meeting density thresholds of at least 385 housing units per square mile.
Urban areas are classified into two types: Urbanized Areas (population 50,000+) and Urban Clusters (population 2,500-49,999). Together they cover about 3% of U.S. land area but contain over 80% of the population.
In ZIP code data, the urban/rural classification helps segment markets, plan delivery routes, and allocate federal funding. Many ZIP codes contain both urban and rural territory.