2015 ACS 1-year and 2011-2015 ACS 5-year Data Releases: Technical Documentation
1.1 The American Community Survey
The American Community Survey (ACS) is a part of the U.S. Census Bureau's Decennial Census Program and is designed to provide more current demographic, social, economic, and housing estimates throughout the decade. The ACS provides information on more than 40 topics, including education, language ability, the foreign-born, marital status, migration and many more. Each year the survey randomly samples around 3.5 million addresses and produces statistics that cover 1-year and 5-year periods 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 our main page at: http://www.census.gov/acs. ACS data are published through a number of channels, including American FactFinder, QuickFacts, Easy Stats as well as the Census Bureaus Application Programming Interface (API). This document will brief data users on the contents of the ACS Summary File and explain how they can use it to obtain statistics.
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 ACS Summary File.
Since the Detailed Tables contain a large number of 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 (or metadata) is in other files, including the Sequence Number and Table Number Lookup file and templates, that the user must merge with the data files to reproduce the tables. Learn more about the Sequence Number and Table Number Lookup file in Chapter 2.3. and the templates in Chapter 2.2.
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 and comma delimited)
Geographies - (position based and comma delimited)
Margins of Error - (comma delimited)
Chapter 2 discusses each component in detail and explains how to put them all together.
Data contained in the ACS Summary File cover demographic, social, economic, and housing subject areas. All Detailed Tables for the ACS 1-year and 5-year estimates are in the Summary File and are listed in Appendix A for their respective data release.
The ACS Summary File covers geographic areas 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.
The ACS 1-year estimates are published for areas that have populations above 65,000. The ACS 3-year estimates are no longer published, but historically covered areas with populations above 20,000. The ACS 5-year estimates are published for all geographic areas, including census tracts, block groups, American Indian areas, core based statistical areas, combined statistical areas, Congressional districts, and state legislative districts. View the full list of summary levels published for the Detailed Tables in Appendix B. Data for census block groups are published in American FactFinder, the Census Bureau API, as well as the ACS Summary File. The list of tables in the 5-year Appendix A shows which tables are available at the block group level.
Since using the ACS Summary File can be challenging, it is recommended that users first check if their tables of interest are available for download on American FactFinder (AFF). Below are some other options to help users retrieve the tables they want. They are listed in order based on ease of use. You can access these tools, as well as instructions on how to access ACS estimates using the AFF Download Center, on the ACS Summary File Documentation page at http://www.census.gov/programs-surveys/acs/technical-documentation/summary-filedocumentation.html.
Summary File Excel Import Tool
The Summary File Excel Import Tool is a replicate of the Excel templates that Census 2000 provided for the Summary File 3 release. The Excel Import Tool provides a basic layout of each sequence in Excel in the same format as the estimate and margin of error files are formatted. A detailed description of a sequence is available in Chapter 2.3.For individuals that do not have Excel 2007 or later and are unable to use the Summary File Retrieval Tool, the Excel Import Tool provides an alternative option to read the ACS Summary File into Excel. You can access instructions for using this tool on the ACS Summary File Documentation page.
There are two programming options for SAS users. The first option is a set of individual SAS programs, one for each summary file by geography and sequence. These programs are best for users only interested in looking at a specific sequence for a specific geography. The second option is a single SAS program that is parameterized to allow users to read in any sequence for any geography into SAS. This program can also be used to read the entire summary file into SAS, and is designed for users looking for a large amount of data. You can access these programs on the Summary File Documentation page.
DataFerrett is a tool provided by the Census Bureau to help users view, download, and manipulate a wide variety of data sets to suit their needs. Among the features provided by this tool is the ability to construct user-defined variables from the variables on the input data file(s), the ability for users to exclude data that is not of interest, a variety of options for downloading data, and the ability to create complex tabular reports from the data including graphs and thematic maps. This tool is ideal for data users who wish to view, customize, and restrict the data that is available in the ACS 5-year Summary File. A link to this tool is available on the Summary File page.
Please send any technical questions or comments on the ACS Summary File you have via email to: firstname.lastname@example.org. If you have questions or comments about the American Community Survey, you can submit a question online at ask.census.gov/.