In 2008 two types of estimates are available from the American Community Survey: one-year estimates (based on data collected in a single year) and three-year estimates (based on data collected in three consecutive years). To help users determine which estimates to select, a basic comparison of one-year and three-year estimates is provided below. Additional information about the interpretation and use of one-year and three-year estimates is available on the ACS website.
The 2007 ACS one-year estimates are based on data collected between January 2007 and December 2007.
The 2005-2007 ACS three-year estimates are based on data collected between January 2005 and December 2007.
For areas with a population less than 20,000, five-year estimates will be available. The first five-year estimates based on ACS data collected from 2005 through 2009 will be released in 2010.