U.S. Census of Population and Housing Basics : Surveys & Data Sets

In Census language, a survey is "a data collection activity involving observation or questionnaires for a sample of a population. (A census is a 100-percent sample survey; it collects information about every member of a population." (Entry from the Census Glossary.)

Examples of surveys:

• American Community Survey
• Annual Survey of Manufacturers
• Decennial Census of Population and Housing
• Economic Census

The Decennial Census of Population and Housing is a 100% survey; it collects information about every member of a population.

As of January 2021, data from the 2020 Decennial Census is being tabulated and verified.  It is not yet available to the public.  See the Important Dates page from the Census Bureau for updates on data availability from the 2020 Decennial Census.

Previous Decennial Censuses

In 2010, the Census Bureau collected the following information about every person in the country:

In recent Decennial Censuses before 2010, the questionnaire people filled out to collect this information was called the short form. Sample data was collected via the long form. With the 2010 Census, the American Community Survey replaced the long form.

Data from the 100% survey is made available via

• Summary File 1, with cross-tabulations of

  Age Sex Households

  Families Relationship to householder Housing units

  Detailed race Detailed Hispanic or Latino origin groups Group quarters

• Summary File 2 makes the data from Summary File 1 available for specific race and ethnic groups within a community.

Starting with the 1940 Census, and ending with the 2000 Census, the Census Bureau used sampling techniques to develop more data on the U.S. population.

Sampling meant asking additional questions of a subset, or sample, of the population during the Decennial Census, then used weighting formulas so the data would be representative of the larger population.

The additional questions asked of the sample of the population changed over time (see Decennial Census of Population and Housing Questionnaires & Instructions to find questions asked over the years), but included more questions on demographics (like what country a person was born in) and housing (like number of rooms in a house), as well as questions about educational attainment, income, employment, and veteran status.

For the 1990 and 2000 Decennial Censuses, sample data was published in Summary File 3 and 4 products.

In 2005, the Census Bureau started collecting detailed data from a sample of the population via the American Community Survey (ACS) (a bit of its history), which is an ongoing survey which provides data more frequently than the Decennial Census. It is sent to a small percentage of the population on a rotating basis throughout the decade. No household will receive the survey more often than once every five years.

The American Community Survey asks questions about

Here's a more detailed list of subjects covered  by the ACS (page from the Census Bureau).

Frequency of ACS
American Community Survey 1- and 5-year estimates are period estimates, which means they represent the characteristics of the population and housing over a specific data collection period. Data are combined to produce 12 months (1 year),  or 60 months (5 years) of data.

There will be times when more than one ACS data set is available for an area. For guidance on when to use which data set, see the Census Bureau's page When to use 1-year, 3-year, or 5-year estimates. It means striking a balance between currency and sample size/reliability/precision.

The ACS did provide 3-year estimates between 2005 and 2013, but those have been discontinued.  Data was collected over 36 months, and produced for areas with populations of 20,000+ .

Comparing ACS Data: Guide from the Census Bureau on comparing ACS data from different ACS data sets, as well as 2010 and 2000 Decennial Census sets https://www.census.gov/programs-surveys/acs/guidance/comparing-acs-data.html

Different surveys ask different sets of questions.

Surveys are taken at different times.

Different surveys ask questions of different sets of people.