The Table-Based ACS Summary File contains three file types:

Table Labels - Description of each line item in a table for 1-year or 5-year data release

    Example File Name: ACS20211YR_Table_Shells.txt or      ACS20215YR_Table_Shells.txt
    Example: B01001_003 = “SEX BY AGE - Total Males Under 5 Years”

​Geography Labels - All geography labels for 1-year or 5-year data release

    Example File Name: Geos20211YR.txt or Geos20215YR.txt 
    Example: 0400000US06 = “California”

Data Files - Data (including estimates, margins of error, and geographies) organized by table ID for 1-year or 5-year release
    Folder: 1YRData, 5YRData
    Example: The file acsdt1y2021-b01001.dat, variable B01001_E003      for 0400000US06 = 1,129,355

There are a variety of resources available for understanding and using the table-based format. Below is a link to the FTP site to access data and documentation, links to webinars related to the table-based format, examples for using SAS and Python, instructions on using geography files with the summary file, and a link to find ACS Table Lists.

Find examples using SAS and Python. Additionally, there are instructions for using the ACS Summary File with Excel.

Visit the Table List webpage for documentation including table IDs, titles, universes, and 1-year/5-year availability for ACS Tables in one spreadsheet.