In general, the U.S. population continues to grow older with a median age over 40 years old in many states. At the same time, increases in the number of men at older ages are apparent. Understanding a population’s age composition, usually examined by sex, yields insights into changing population conditions and can highlight future social and economic trends. See the information on which survey and programs collect these data.

The purpose of this two-part question frequently used in Census Bureau questionnaires is to ensure accuracy of age data and to minimize non-response rates. Because age is a critical element in determining federal funding, it is imperative to have high quality age data. Age is also a basic demographic characteristic that is crossed by social characteristics, such as marital status and education, and economic characteristics, such as labor force participation and poverty, in many data products. Especially because of the multiple uses of age data and their visibility, it is important that they be of high quality. Asking for both date of birth in month, day, and year format, along with age, helps to ensure that quality.

For assistance, please contact the Census Call Center at 1-800-923-8282 (toll free) or visit ask.census.gov for further information.