Census Block Group

Dataset

Description

A geographic unit used by the US Census Bureau for publishing census and other demographic/economic data. It consists of a cluster of blocks within the same census tract. Each census block group is usually a contiguous area and never crosses tract, county, or state boundaries.

Sourcing

Census Blocks Groups are assigned by the US Census Department. They change every ten years to coincide with a new census. The US Census Bureau tries to keep the population of a Census Tract to 4,000 people. If at the time of a new census the population of a Census Tract has reached or exceeded 8,000 people, it will be split up into multiple tracts. This will trigger a new set of Census Blocks Groups being assigned to many properties in the original Census Tract.

ATTOM has a library of shape files that define the boundary of each Block Group. We have used those shape files to analyze 150 million properties and establish which block group each property falls within. Unless you have a specific need for the shapefiles you can take advantage of ATTOM's geocoding to purchase the lookup table that matches properties to Census Blocks.

Note: Because property lines are used as one of the criteria for defining a Census Block, a property should only fall within one Census Block Group.

Tables/Views

The following tables can be used to access Census Block information. When delivering solutions to customers, some or all of the information found in these tables may be consolidated into one or more views.

DimBlockGroup

A register of US census blocks groups, including their size and location.

Rows: 220K
Columns: 20
Family: Boundary
Type: Area
Geography Type: 32

PropertyBoundaryMatch

The PropertyBoundaryMatch table can be used to:

• Identify the census block group for a specific property; and
• Get a list of the properties that fall within a census block group

Dimension Tables

The following dimension tables provide lookups for various codes contained in the tables/views used by this data element.

DimGeographyType: The complete list of geography types used as boundaries as well as the dimension table used to provide details about each boundary

Product Articles (P-Articles)

All solution packs containing the Census Block data element will include the following p-articles to help you understand and use the data: -

• Census Boundaries 101