Census

A census is a data collection activity that is usually periodic and is typically conducted by a governmental entity for the purpose of obtaining statistical information and producing data for the entire population. A census contrasts with a survey, which uses sampling methods and obtains information from a subset of rather than the entire population. In the United States, the term census is commonly associated with the Decennial Census of Population and Housing, which takes place every 10 years and is conducted by the U.S. Census Bureau for the purpose of counting the population to apportion the seats in the House of Representatives among the states and to provide small-area data necessary for legislative redistricting.

Many countries conduct periodic censuses for their populations; their design, the data collection methods, and the data produced vary. Not all censuses focus on counting populations and housing units. For example, in addition to a census of population and housing, the U.S. Census Bureau conducts an economic census, which collects information on the characteristics of businesses, and a census of governments, which collects data on the finances and administrative characteristics of state and local governments.

Censuses are critical to and depend on the discipline of geography. Census activities rely heavily on geographic databases and geographic information system software as well as cartographic operations. Census data, based on the areas defined and maintained by the U.S. Census Bureau and statistical agencies in other countries, are widely used throughout the geospatial industry, in geography programs in academia, and throughout the public and private sector, wherever geography is practiced. This entry focuses on the U.S. Census of Population and Housing.

Article 1, Section 2, of the U.S. Constitution requires enumeration of the nation's population every 10 years. The United States has conducted censuses every decade since 1790; the scope of the census, the methods used, and the data tabulations produced have evolved over time.

Census 2000 collected basic information (name, household relationship, sex, age, Hispanic or Latino origin, race, and tenure—whether a home is owned or rented) for all people and housing units and detailed information on demographic, social, housing, and economic characteristics for people and housing units through a sample survey conducted as part of the decennial census. The 2010 Census collected basic information for people and housing units. However, detailed information was collected through the American Community Survey (ACS). The ACS is an ongoing survey that has replaced the sample survey used for Census 2000 and previous censuses and produces timely demographic, social, housing, and economic data (Table 1).

Like previous censuses, the 2010 Census required a full range of preparations that included the testing of concepts that are the basis for census questions, improvements to address lists, various promotional activities, a variety of technological improvements, the dissemination of data products, and other activities. Twelve regional offices located in major cities throughout the United States provided critical support to local operations, including hiring and data collection. The Census Bureau made significant efforts to develop effective partnerships with local communities and organizations to encourage full participation and to communicate a commitment to respecting privacy and protecting the confidentiality of the data collected. Title 13, United States Code, is the basis for the Census Bureau's commitment to safeguarding data. Most addresses received an English language questionnaire, although a bilingual Spanish-English questionnaire was mailed to selected areas. Then, to assist people who do not speak English well, the Census Bureau provided translated forms in five languages (Spanish, simplified Chinese, Vietnamese, Korean, and Russian), telephone questionnaire assistance in those same languages, and language assistance guides in 59 languages. Promotional and outreach materials were provided in many languages.

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