Population density, or population per square mile (land area), is a by-product of population growth, and indicates where growth occurs within the county. Monitoring changes in population densities provides an opportunity to assess land use in urban, suburban, and rural areas. Urban areas have population densities measuring at least 3,000 people per square mile, and are expected to have a concentrated mix of housing, retail, education, medical, recreation, and transportation options. Communities measuring below 1,000 people per square mile are rural areas, where residences and amenities are spread farther apart from each other, as the land is used primarily for agriculture, forestry, and horticulture. Population density impacts costs of service provision, as government and business investments are made based on the efficiency and expense of marketing, distributing, or serving populations over the expanse of a geographic service area.

Wake County's population density ranked 8th among the nation's top 10 counties with at least 1 million residents with a growth rate of at least 10% between 2010 and 2015.

Wake County's population density increased by almost 500 additional people per square mile of land area between 2000 and 2015.

The United States Census Bureau publishes official population estimates and population estimate revisions for prior years annually. County, state, and national data are released in March. Municipal data for population density are updated on census years only; the most recent census year was 2010.

September 2015: Revised to reflect 2014 ACS estimates for county, state, and national data.