Using the American Community Survey Table-Based Summary File - Chapter 2 - How to Use the ACS Table-Based Summary File

Sep 21, 2026

Explains how to locate and use the American Community Survey (ACS) Table-Based Summary File on the U.S. Census Bureau site and through its file transfer protocol. Describes the file format (pipe-delimited UTF-8) and the three main components: table labels (table shells), geography labels, and data files. Details organization of 1-year and 5-year releases, including folder names, naming conventions, and examples of data and label variables.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages8

Reading Time20 min

AccessFree to download

How to Use the ACS Table-Based Summary File

Locating the ACS Summary File

File format and components

Data files (1-year and 5-year)

Geography labels (GEO_ID matching)

Table labels (table shells)

Naming conventions for ACS data files

2. HOW TO USE THE ACS TABLE-BASED SUMMARY FILE The American Community Survey (ACS) Summary File is located on the U. S. Census Bureau’s ﬁle transfer protocol server.10 The easiest way to ﬁnd the ﬁle is to start at the ACS website.11 From the ACS main page <[www.census.gov/programs](www.census.gov/programs)surveys/acs >, select the “Data” navigation link on the left. From there, click on the “Summary File”navigation link on the left, as shown in Figure 2.1. The ACS Table-Based Summary File is in pipedelimited, Unicode Transformation Format (UTF- 8), which can easily be imported into software packages. The ﬁle is divided into three components: table labels (or table shells), geography labels 10 U. S. Census Bureau,“American Community Survey Data via the File Transfer Protocol Server," <[www.census.gov/programs-surveys/](www.census.gov/programs-surveys/)[ ](www.census.gov/programs-surveys/)[acs/data/data-via-ftp.html](acs/data/data-via-ftp.html)> . 11 U. S. Census Bureau,“American Community Survey," . (or geography ﬁles), and data ﬁles. This section describes the components of the Summary File and the next section provides information and resources to put them together. • Data ﬁles: Data (including estimates, margins of error, and geographies) organized by table ID for the 1-year or 5-year release: ° Folder: 1YRData, 5YRData. ° Example: The ﬁle acsdt1y2021-b01001 .dat, variable B01001_E003 for 0400000US06 = 1,129,355 . • Geography labels (or geography ﬁles): All geography labels for the 1-year or 5-year data release: ° File name example: Geos20211YR.txt or Geos20215YR.txt. ° Variable label example: 0400000US06 =“California.” | Figure 2.1. Locating the American Community Survey Summary File | | --- | | | | Source: U. S. Census Bureau,“American Community Survey Data," <[www.census.gov/programs-surveys/acs/data.html](www.census.gov/programs-surveys/acs/data.html)> . | Using the American Community Survey Table-Based Summary File 5 U. S. Census Bureau What All Data Users Need to Know | Figure 2.2. American Community Survey Summary File Components Associated With the 2021 Data Release | | --- | | | | Source: U. S. Census Bureau,“American Community Survey Summary File," <[www.census.gov/programs-surveys/acs/data/summary-](www.census.gov/programs-surveys/acs/data/summary-)ﬁle.2021. html\#list-tab-1622397667> . | • Table labels (or table shells): A description of each line item in a table for the 1-year or 5-year data release: ° File name example: ACS20211YR_Table_Shells.txt or ACS20215YR_Table_Shells.txt. ° Variable label example: B01001_003 = “SEX BY AGE – Total Males Under 5 Years.” Figure 2.2 shows the location of each of these components on the Census Bureau’s ACS Summary File website (2021 data release) . Data Files Under the new table-based format, the ACS Summary File is organized by individual Detailed Tables that can be downloaded separately. Each data ﬁle contains estimates and margins of error (MOEs) for all available geographies. Figure 2.3 lists a compressed ﬁle of the entire dataset. Table 2.1 lists the naming convention used for aselected ﬁle in the 1-year data directory (for 2021) . The ﬁle name,“acsdt1y,” refers to the ACS 1-year Detailed Tables; “2021” refers to the data collection year; and“b01001” refers to the table ID. Figure 2.4 lists the ﬁrst few rows from a 2017–2021 ACS 5-year Summary File estimate for “Table B08121: Median Earnings in the Past 12 Months (In 2021 Inﬂation-Adjusted Dollars) by Means of Transportation to Work.” The ﬁrst row of the pipe-delimited ﬁle lists the variable labels, while subsequent rows list the ACS estimates for this table. The rows highlighted in the table list the results for the United States, rural areas, and the Midwest region (spotlighted in the“Geography Files” subsection) . The directory for the ACS 1-year Summary File is organized in a similar fashion.

FAQs

Where can the ACS Table-Based Summary File be found?

It is hosted on the U.S. Census Bureau file transfer protocol server. The easiest route starts from the ACS website, then navigates to “Summary File” under the left-side menu.

What are the main components of the ACS Table-Based Summary File?

The summary file is divided into table labels (table shells), geography labels (geography files), and data files. Together they let users interpret table rows and align results to geographic identifiers.

How are ACS 1-year and 5-year data files organized and named?

Data files are stored in folders such as 1YRData and 5YRData and organized by table ID. The naming convention uses the pattern acsdt1y[year]-[tableID].dat, where dt indicates detailed tables and 1y or 5y indicates the period covered.

Sep 21, 2026

Uploaded by Lucas Martin