The TIGER/Line shapefiles and related database files (.dbf) are an extract of selected geographic and cartographic information from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). The MTDB represents a seamless national file with no overlaps or gaps between parts, however, each TIGER/Line shapefile is designed to stand alone as an independent data set, or they can be combined to cover the entire nation.

This data set represents the boundaries of the 2020 Census Block Groups, extracted from the MTDB in 2020. The feature class was re-projected from the Census Bureau shapefile tl_2020_34_bg20.shp .

Block Groups (BGs) are defined before tabulation block delineation and numbering, but are clusters of blocks within the same census tract that have the same first digit of their 4-digit census block number from the same decennial census. A BG usually covers a contiguous area. BGs never cross county or census tract boundaries. The BG boundaries in this release were delineated as part of the Census Bureau's Participant Statistical Areas Program (PSAP) for the 2020 Census.

For additional references to explain the data, see Supplemental Information.