The U.S. Census Bureau estimates of U.S. population consist of both incorporated places, such as cities, boroughs, and villages, and minor civil divisions such as towns and townships. The Census Bureau produces subcounty population estimates by a housing unit method that uses housing unit change to distribute county population to subcounty areas. In addition to their use in producing subcounty population estimates, housing unit estimates at the subcounty level are aggregated to the county and state levels and released as a separate data product.
City and unincorporated area estimates are based on an estimates of total and occupied housing units, household size and population, and group quarters population. The number of housing units is based on reported construction of new housing units. The state population is estimated taking into changes in drivers licenses issued, annual births and deaths, tax return data, Medicare enrollment, and immigration data.
The benchmark for both estimates is the 2000 Census of Population and Housing. Some aggregated numbers may not sum due to rounding.