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American Community Survey (ACS)

When to Use 1-year, 3-year, or 5-year Estimates

Choosing which dataset involves more than simply considering the population size in your area. You must think about the balance between currency and sample size/reliability/precision. For details, research implications, and examples, see "Understanding and Using ACS Single-Year and Multiyear Estimates," in section 3 of the General Data Users Handbook.

Distinguishing features of ACS 1-year, 1-year supplemental, 3-year, and 5-year estimates

1-year estimates
1-year supplemental estimates
3-year estimates*
5-year estimates
12 months of collected data Example: 2017 ACS 1-year estimates Date collected between: January 1, 2017 and
December 31, 2017
 12 months of collected data Example: 2017 ACS 1-year supplemental estimates Date collected between: January 1, 2017 and
December 31, 2017
 36 months of collected data Example: 2011-2013 ACS 3-year estimates Date collected between: January 1, 2011 and
December 31, 2013
 60 months of collected data Example: 2013-2017 ACS 5-year estimates Date collected between: January 1, 2013 and
December 31, 2017
Data for areas with populations of 65,000+
 Data for areas with populations of 20,000+ Data for areas with populations of 20,000+
 Data for all areas
Smallest sample size Smallest sample size Larger sample size than 1-year Largest sample size
Less reliable than 3-year or 5-year Less reliable than 5-year More reliable than 1-year; less reliable than 5-year Most reliable
Most current data Most current data Less current than 1-year estimates; more current than 5-year Least current
Annually released: 2005-present
 Annually released: 2014-present Annually released: 2007-2013 Annually released: 2009-present
Best used when
Best used when
Best used when
Best used when
Currency is more important than precision Analyzing large populations Currency is more important than precision Analyzing smaller populations Examining smaller geographies because the standard 1-year estimates are not available More precise than 1-year, spans fewer years than 5-year Analyzing smaller populations Examining smaller geographies because the standard 1-year estimates are not available Precision is more important than currency Analyzing very small populations Examining tracts and other smaller geographies because 1-year estimates are not available

*ACS 3-year estimates have been discontinued. The 2005-2007, 2006-2008, 2007-2009, 2008-2010, 2009-2011, 2010-2012 and 2011-2013 ACS 3-year estimates will remain available to data users, but no new 3-year estimates will be produced. Every community in the nation will continue to receive a detailed statistical portrait of its social, economic, housing and demographic characteristics through 1-year and 5-year ACS products.

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