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 handbook "Understanding and Using ACS Data: What All Data Users Need to Know."

Publication

Understanding and Using ACS Data: What All Data Users Need to Know

September 2020

This handbook helps general data users learn how to access and use ACS data and provide concrete examples of how ACS data can answer real-world questions.

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: 2021 ACS 1-year estimates Date collected between: January 1, 2021 and December 31, 2021	12 months of collected data Example: 2021 ACS 1-year supplemental estimates Date collected between: January 1, 2021 and December 31, 2021	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: 2017-2021 ACS 5-year estimates Date collected between: January 1, 2017 and December 31, 2021
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.

Related Information

American Community Survey Data

Sample ACS & PRCS Forms and Instructions