The Department is a major repository for census and statistical data, and works closely with the U.S. Census Bureau and other government statistical agencies. Information collected from the census is used to distribute over $300 billion in federal funding to states and local governments. In addition, census information determines how many seats each state receives in the U.S. House of Representatives and how many electoral votes each state receives for presidential elections. Funding and planning for schools, infrastructure, and community programs and services relies on census data.
The Decennial Census
The census is conducted every ten years, as required by the Constitution. Census forms are sent to every household in the nation. Everyone is required to be counted in the census, including persons of all ages, racial backgrounds, citizens and non-citizens. For households that do not return census forms, the Census Bureau may make official visits to count the individuals living in those households.
Data from the census is anonymized and cannot be traced back to any individual person. Sharing personal census information outside the Department of Commerce (i.e., with local and federal law enforcement, tax agencies, etc.) is illegal, and punishable by up to 5 years in prison and a $250,000 fine.
About the American Community Survey
The Census Bureau previously sent a "long form" of the Census to a sample of the population along with the "short form" of the decennial census. This form included a more extensive list of questions beyond the 10 identified in the short form of the Census. Beginning in 2005, the Bureau began to use a new sample survey known as the American Community Survey (ACS). This survey is now sent to approximately 3.5 million housing units and group quarters in the US annually. ACS estimates are less precise than the comparable estimates from Census 2000 and prior decennial census years, however they are collected each year and are at times more current. It is necessary to combine multiple survey years to obtain reliable estimates for smaller geographies. All ACS data is subject to a margin of error, as was true for long form Census 2000 sample data.