Skip to Main Content
It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.

U.S. Census Research Guide: American Community Survey

The U.S. Census Bureau conducts several data collection programs about the U.S. population which have their own language, geography, and data portals. This guide is based on a similar guide created by Kelly Smith at UCSD.

ACS Logo


2020 ACS 1-Year Experimental Data Release

2020 ACS 1-Year Experimental Data FAQ

The Census Bureau is releasing these experimental data instead of the 2020 ACS 1-year estimates, which were negatively impacted by the COVID-19 pandemic. This will include a limited number of data tables for the nation, states, and the District of Columbia.  This data will NOT be available via, only at this site. 

American Community Survey (ACS)

About the American Community Survey (ACS)

The American Community Survey (ACS) is an ongoing survey conducted by the U.S. Census Bureau since 2005. In 2010, the ACS replaced the decennial Census long form as the source of sample data for population and housing indicators. The short form of the decennial Census is still distributed to obtain a count of the entire U.S. population.

ACS asks questions about age, sex, race, family and relationships, income and benefits, health insurance, education, veteran status, disabilities, employment location and mode of travel to work, place of residence, price paid for living essentials. You can review the annual questionnaires to see the precise questions asked each year.

There are both benefits and challenges associated with replacing the long form with ACS. The primary benefit is the freshness of data: ACS data is collected every year, whereas the decennial Census was collected every ten years. Challenges include a higher sampling error for the ACS, due to a smaller sample population, and difficulties comparing data from year to year.

Finding ACS Data & Statistics

ACS data is incorporated into, the Census Bureau's primary data tool, with a variety of access points:

Northwestern University affiliates can find ACS data and maps in the Social Explorer database, and a selection of tables/reports in ProQuest Statistical Insight.

NUSearch lists several ACS briefs and reports, most of which are available online.  ACS Reports are also provided by the Census Bureau.  Examples of titles produced in 2015 -- Who Drives to Work?; Young Adult Migration; Remarriage in the United States.

The Census Bureau provides Guidance for Data Users, options to download data via FTP, and Public Use Microdata Samples (PUMS).

Digitized Data Source

ACS Estimates

Each year, the Census Bureau releases 1- and 5-year estimates based on information gathered in the ACS.  3-year estimates were discontinued in 2014.  Data from the 3-year estimates collected 2005-2013 will remain available, e.g. 2005-2007, 2006-2008, 2007-2009, 2008-2010, 2009-2011, 2010-2012, 2011-2013.

In deciding which estimate you want to use, you should consider a) the currency of data; b) the geographic size of your population; and c) the acceptable sample size/reliability of the data.  The Census Bureau chart below shows distinguishing features of the different estimates.

Important note: if you wish to compare ACS estimates to earlier decennial Census data, please review these cautions first.

  • Comparing ACS Estimates
  • Statistical Test Tool to determine the significance of data compared
  • Comparitive tables are available in the American FactFinder - use the Advanced Search and enter these table numbers:
    • CP02 - Social Characteristics
    • CP03 - Economic Characteristics
    • CP04 - Housing Characteristics
    • CP05 - Demographic Characteristics

Understanding and Using American Community Survey Data: What All Users Need to Know.  [PDF July 2018]