Census Tract, Block Group & Block Geography

Census tracts, block groups and blocks are the important small area statistical geographic areas for which data from Census 2010 are tabulated. Data for census tracts and block groups are now tabulated annually from the American Community Survey. For example. in December 2014, we will have new “richer demographics” annual estimates centric to each year 2008 through 2011 for Census 2010 tracts and block groups … data such as educational attainment, median household income and median housing value.

These areas cover the U.S. from wall-to-wall and generally non-changing in terms of boundary and geographic code (geocode) until Census 2020. This section provides a summary of new Web pages with more detail about each of these geographies:
census tracts and tract codes
census block groups and block group codes
census blocks and block codes

Each of these pages provides an interactive table to view tallies of Census 2010 for each of these small area geographies.

Combining Address Data with Small Area Geography
The address of the Office of the California Secretary of State, located at 1500 11th St, Sacramento, CA 95814, was geocoded using the APIGeocoder and converted into a shapefile for Geographic Information System applications.  The location is shown as a red marker in the map views shown below, illustrating each type of small area geography: tracts. block groups and blocks.

Census Tracts
Tracts are labeled with green tract codes. Address 1500 11th St, Sacramento, CA 95814 is shown by red marker.  The address is in tract 06067001101.

View created using CV XE GIS.

Block Groups
Block groups are labeled with red block group codes.  Tract 06067001101 is comprised of block groups: 060670011011 and 060670011012.  See pointer in map view; the block group within tract boundary.

View created using CV XE GIS.

Zoom-in to Census Block
Blocks are labeled with yellow block codes. The address is located in block 060670011011085.

View created using CV XE GIS.

Further Zoom-in Showing Streets
Streets are labeled with street names. Identify tool is used to show mini-profile for 1500 block of 11th Street.

View created using CV XE GIS.

Is the tract code 11.01 or 001101?
Both. Census tracts within a county are identified by a 4-digit basic code between 0001 and 9999, and may have a 2-digit suffix ranging from .01 to .98; for example, 6059.02. The decimal point separating the 4-digit basic tract code from the 2-digit suffix is shown in Census Bureau printed reports and maps. For geo-referencing, the decimal point is implied and does not appear; the 6-character tract code with lead zeroes is used — a character string with no blanks and all numbers.

Decision-Making Information Web Sessions
Learn more about using resources described in this section. Join us in a Decision-Making Information Web session. There is no fee for these one-hour Web sessions. Each informal session is focused on a specific topic. The open structure also provides for Q&A and discussion of application issues of interest to participants. We can address your specific questions about tools to visually analyze patterns.

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