Documentation: | ACS 2009 (5-Year Estimates) |
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Publisher: U.S. Census Bureau
Survey: ACS 2009 (5-Year Estimates)
Document: | ACS 2009-5yr Summary File: Technical Documentation |
citation: | Social Explorer; U.S. Census Bureau; American Community Survey 2005-2009 Summary File: Technical Documentation. |
Chapter Contents
The American Community Survey (ACS) is a household survey conducted by the U.S. Census Bureau with an annual sample size of about 3 million addresses. The ACS data provides communities with the current information they need to plan investments and services. Information from the survey generates data that help determine how more than $400 billion in federal and state funds are distributed annually. Each year the survey produces data that cover the periods of 1-year, 3-year, and 5-year estimates for geographic areas in the United States and Puerto Rico, ranging from neighborhoods to Congressional districts to the entire nation. For more, information about the ACS, please visit www.census.gov/acs.
Most ACS tables are published on the Census Bureau's American FactFinder (AFF) website, factfinder.census.gov, and are available for download in several forms. However, for the 2005-2009 ACS 5-year data release, 295 Detailed Tables and tables for census block groups are not published on American FactFinder. These tables can only be accessed by using the ACS Summary File. This document will brief data users on the contents of the ACS Summary File and explain how they can use it to obtain the 5-year estimates.
Most ACS tables are published on the Census Bureau's American FactFinder (AFF) website, factfinder.census.gov, and are available for download in several forms. However, for the 2005-2009 ACS 5-year data release, 295 Detailed Tables and tables for census block groups are not published on American FactFinder. These tables can only be accessed by using the ACS Summary File. This document will brief data users on the contents of the ACS Summary File and explain how they can use it to obtain the 5-year estimates.
The American Community Survey Summary File (ACSSF) is a unique data product that includes all the estimates and margins of error from the Detailed Tables and geographies that are published for the ACS. Other ACS data products such as Subject Tables and Data Profiles are created from the Detailed Tables and are therefore not available in the Summary File.
Since the Detailed Tables contain over 18 billion cells, the tables are stored in a series of files with only the data from the tables, without such information as the title of the tables, the description of the rows, and the names of the geographic areas. That information is in other files that the user must merge with the data files to reproduce the tables.
The ACS Summary File data files are in American Standard Code for Information Interchange (ASCII) format. The files are divided into three types:
Since the Detailed Tables contain over 18 billion cells, the tables are stored in a series of files with only the data from the tables, without such information as the title of the tables, the description of the rows, and the names of the geographic areas. That information is in other files that the user must merge with the data files to reproduce the tables.
The ACS Summary File data files are in American Standard Code for Information Interchange (ASCII) format. The files are divided into three types:
- Geographies - (position based)
- Estimates - (comma delimited)
- Margins of Error - (comma delimited)
Data contained in the ACS Summary File cover demographic, social, economic, and housing subject areas. All Detailed Tables for the ACS 5-year estimates are in the Summary File and are listed in Appendix E. This appendix also shows whether a table is available for download on American FactFinder.
The published ACS Summary File geographies cover areas that are based on "summary levels". A summary level specifies the content and the hierarchical relationships of the geographic elements that are required to tabulate and summarize data. For example, summary level code "040" represents the U.S. States, Washington D.C., and Puerto Rico; while summary level code "050" represents counties and county equivalents within states. Many resources are available to help users understand the ACS geographic terms and concepts. For additional information, please visit www.census.gov/geo/www/reference.html.
In addition to the ACS 1-year and 3-year summary levels, new summary levels are added to the 5-year data with expanded geographies including census tracts and block groups, and additional information for geographies such as American Indian areas, core based statistical areas, combined statistical areas, Congressional districts and state legislative districts. See the full list of summary levels published for the 5-year Detailed Tables in Appendix F. For the 2005-2009 ACS 5-year data release, data for census block groups are not published on American FactFinder and are only available using the ACS Summary File. The list of tables in Appendix E shows which tables are available at the block group level.
There are 295 Detailed Tables that are not available on American FactFinder, which are documented in Appendix E. All Detailed Tables, including those 295 tables, are available for download in comma-delimited format, which can be easily read into a spreadsheet, at www2.census.gov/acs2009_5yr/prod. The Data Profiles and Subject Tables are also available on this site.
The published ACS Summary File geographies cover areas that are based on "summary levels". A summary level specifies the content and the hierarchical relationships of the geographic elements that are required to tabulate and summarize data. For example, summary level code "040" represents the U.S. States, Washington D.C., and Puerto Rico; while summary level code "050" represents counties and county equivalents within states. Many resources are available to help users understand the ACS geographic terms and concepts. For additional information, please visit www.census.gov/geo/www/reference.html.
In addition to the ACS 1-year and 3-year summary levels, new summary levels are added to the 5-year data with expanded geographies including census tracts and block groups, and additional information for geographies such as American Indian areas, core based statistical areas, combined statistical areas, Congressional districts and state legislative districts. See the full list of summary levels published for the 5-year Detailed Tables in Appendix F. For the 2005-2009 ACS 5-year data release, data for census block groups are not published on American FactFinder and are only available using the ACS Summary File. The list of tables in Appendix E shows which tables are available at the block group level.
There are 295 Detailed Tables that are not available on American FactFinder, which are documented in Appendix E. All Detailed Tables, including those 295 tables, are available for download in comma-delimited format, which can be easily read into a spreadsheet, at www2.census.gov/acs2009_5yr/prod. The Data Profiles and Subject Tables are also available on this site.
Since using the ACS Summary File can be challenging, users should first check if their tables of interest are available for download on American FactFinder. (Up to 7,000 tables can be downloaded at one time using the American FactFinder Download Center.) Below are some other options to help users retrieve the tables they want. They are listed in order based on ease of use.
- Summary File Excel Retrieval Tool
- Summary File Data Ferrett Tool (coming in January 2011)
- Summary File Excel Import Tool
- SAS Programs
For those who have previously used the ACS Summary File, the files for the 5-year estimates are basically the same with the following exceptions:
- Geography Levels are Published Only on the Summary File
- The "merge_5_6" File Has Been Renamed
- Folders Have Been Renamed
Folder Name for the 2009 1-Year Summary File | Folder Name for the 2005-2009 5-Year Summary File |
Entire_SF | 2005-2009 ACSSF_All_In_Two_Giant_Files (Experienced Users Only) |
Entire_States | 2005-2009_ACSSF_By_State_All_Tables |
Seq_by_ST | 2005-2009_ACSSF_by_State_by_Sequence_Table_Subset |
- Summary File Format Has Been Modified
Please send any technical questions or comments on the ACS Summary File you have via email to: acso.users.support@census.gov. If you have questions or comments about the American Community Survey, you can submit a question online at ask.census.gov/.