In 2008, several changes were made to improve the content and data quality of the American Community Survey (ACS). Most of the changes to the 2008 ACS data products are in response to improvements to the 2008 ACS questionnaire and changes to tabulated categories for select topics.

While the 1-year and 3-year data products are generally consistent, not all the changes to the 2008 ACS 1-year data products will be immediately visible in the 2006-2008 ACS 3-year data products.

Additions to the 2008 ACS 1-year data products will not show up in the 3-year data products until the 2008-2010 ACS 3-year data products are released in 2011. This includes all of the new marital history, health insurance coverage, service-connected disability status and ratings, foreign born, relationship, and educational attainment data products as well as two expanded school enrollment detailed tables. It will require three years of data collection before those 3-year data products become available, therefore 3-year estimates will not be available until the 2008-2010 ACS 3-year data products are released in 2011. This includes the 3-year Public Use Microdata Sample (PUMS) files.

All tables removed from the 2008 ACS 1-year data products will also be removed from the 2006-2008 ACS 3-year data products.