The United States Constitution requires a census to be taken every ten years so that the seats in the House of Representatives can be reapportioned to the states in a fair manner. Census data are also used to apportion government funding for various social and economic programs.
Statutes governing the census are contained in Title 13 of the U.S. Code.
The U.S. Census Bureau is the major federal agency responsible for collecting, maintaining, and publishing census data.
In addition to providing a head count of the total U.S. population, the decennial census gathers data on social, demographic, and economic characteristics, including age, sex, race, household relationships, and home ownership.
To supplement the decennial statistics, which become outdated almost as soon as they are published, an American Community Survey, taken from a small sample of the population, provides annual profiles of the U.S. population.
The easiest way to access most of the population, housing, economic, and geographic data collected by the various programs of the Census Bureau is through the American FactFinder. In American FactFinder you can obtain data in the form of maps, tables, and reports from a variety of Census Bureau sources.