The U.S. population continues to grow older, with a median age increasing from 37.2 in 2010 to 38.8 in 2020, resulting from the combined effect of fewer children and larger older age groups (Blakeslee et al., 2023). And, while females continued to outnumber males aged 65 and over, the gap narrowed somewhat over the decade with older males increasing at a faster rate than older females (i.e., a 44.0 percent increase from 2010 to 2020 for males, and a 34.4 percent increase for females) (Caplan et al., 2023). Understanding a population’s changing age and sex composition (see 2010 and 2020 Census age-sex pyramids below), yields insights that can help predict future social and economic trends.

Population numbers for age and sex categories are critical to determining federal funding for a state or area, so it is imperative to have high quality data about these basic characteristics of the U.S. population. Population numbers by age and sex can also be cross-classified with social and economic characteristics to learn how these characteristics can differ by age and sex.

We ask a two-part (i.e., age and date of birth) age question to maximize age data quality. The sex question asks whether the individual is male or female.

Data are available on age and sex through the Population and Housing Unit Estimates, Decennial Census and the American Community Survey. The data.census.gov and Census Survey Explorer are the tools to access data for many of our surveys and programs.

Included here are also some links to specific age and sex data products and tools, including a new data visualization tool where users can visually explore the data for their geographic area of interest.