Decennial Census

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What Is It?

The decennial census is conducted by the U.S. Census Bureau every 10 years to provide a full count of the U.S. population and gather basic information on population, households, and housing characteristics.

The main purpose of the decennial census is to allocate the seats in the U.S. House of Representatives, but it also gives communities the most complete and accurate picture of their population and its basic characteristics.

What Subjects are Covered

The Census Bureau collects decennial census information from a “short form” questionnaire mailed to all households every 10 years.

Key subjects include:

  • Counts of population, households, and housing units
  • Basic demographics (age, sex, race, and Hispanic or Latino origin)
  • Whether people live in households or group quarters
  • Household size and composition
  • Housing occupancy and tenure (owner- or renter-occupied)

What Is Published

The Census Bureau provides decennial census data for Census 2000 and Census 2010. The Census Bureaus has data summaries covering geographic areas that range from the nation to the individual census block at their American FactFinder online data portal.

The City of Seattle provides population and housing information from Census 2010, Census 2000, and prior decennial censuses for the city and its neighborhoods.

The information available includes:

  • Reports and tables of basic demographic information
  • Reference maps and geographic data files including GIS shapefiles

For more information about each census, please see the desired decade on the tabs along the top of this page.

What You Need to Know

In past decades the decennial census also produced estimates on detailed demographic, social, economic, and housing characteristics collected as part of a nationwide sample referred to as the “long form.”

In 2010 the Census Bureau only conducted the 100% count, or “short form,” to collect data used for the allotment of the House of Representatives. The data that in the past was collected by the “long form” is now part of the American Community Survey.

What Else You Should Know

For a more detailed discussion of the differences in the way questions were asked in the 2000 and 2010 censuses, as well as geographic changes that may affect comparability between decennial censuses, please see Data Issues.

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