Census Block

Dataset

Description

The smallest geographic unit used by the US Census Bureau for publishing census and other demographic/economic data. Each census block is bounded by visible features such as streets, roads, rivers, and railroad tracks along with nonvisible boundaries such as property lines, cities and townships, school districts, and counties.

The Census Block is the basic entity common to all other levels of aggregation recognized and used by the US Census Bureau and many other federal agencies: Census Block Groups; Census Tracts; Congressional Districts; Core Based Statistical Areas; Counties; County Subdivisions; Divisions; Nation; Places; Public Use Microdata Areas; Regions; School Districts; State Legislative Districts; States; Subminor Civil Divisions; Traffic Analysis Zones; Urban Areas; Urban Growth Areas; Voting Districts; and Zip Code Tabulation Areas.

Sourcing

Census Blocks 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 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.

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.

DimCensusBlock

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

Rows: 11.2 million
Columns: 23
Family: Boundary
Type: Area
Geography Type: 33

PropertyBoundaryMatch

The PropertyBoundaryMatch table can be used to:

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

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

Matching Data

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