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Census Blocks (2010)

Census Geography Background

The Census Bureau (http://www.census.gov/) maintains geographic boundaries for the analysis and mapping of demographic information across the United States. Every 10 years the Census Bureau counts the population of the United States as mandated by Constitution. The Census Bureau releases the results of this county as demographic data with geographic identifiers so that maps and analysis can be performed on the US population.

For a quick introduction to Census geography, click the thumbnail on the right which shows the relationship between Census Blocks, Block Groups, Tracts, and Counties.

For detailed information about the Census Geography, here are some other links:

LA County Samples



Census Blocks 2010

Zoomed at CSULA

What is unique about LA County’s data?

  1. It is clipped to the ocean boundary. Raw Census data includes a 3 mile buffer into the ocean, which impacts cartography.
  2. Each census blocks are assigned with the community name based on the 2011 redistricting unit community names.
  3. IMPORTANT! It has been updated to re-include Census Tract 1370.00, which the Census Bureau mistakenly merged with tract 8002.04. Note – until the Census Bureau releases updated population files this update will impact population mapping since population tables will not have 13700.00 (it’s population will be part of 8002.04 showing higher numbers than reality). Please see this post on the County Enterprise GIS about this. We have included the raw file for those who want to use it.

Maps showing what changed

General Area

Zoomed in

How was this data created?

This data was downloaded from Census Bureau website: ftp://ftp2.census.gov/geo/pvs/tiger2010st/06_California/06037/ and clipped to the County Boundary using ESRI’s ArcGIS Desktop. A new field “COMMNAME” was added and populated with city and community names based on 2011 redistricting unit community names in the census block data. This dataset has unique identifier field “GEOID10” for each record, and the census tract and census block number combined field “CTCB10”, block group field “BG10” and census block number field “CB10”.

Download/Access the data

Using GIS Data on this site

GIS Data downloaded from this site generally requires GIS software to view. Click here for a list of GIS Data Viewers

GIS data available on this website is provided AS IS - please read the GIS Data Portal Terms of Use

Data Field Descriptions
  • GEOID10: Unique identifier.
  • CTCB10: Census tracts number and census blocks number combined.
  • BG10: Census block groups number.
  • CB10: Census blocks number.
  • X_Center and Y_Center: Centroid of the census block.
  • COMMNAME: Name of the cities and/or communities based on 2011 redistricting unit city/community names.

GIS Source Information
Database Name:
Feature Class Name:
Feature Dataset Name (if applicable):
Reference Date: 2010
Accuracy: TIGER
Update Frequency: As Needed
Access Constraints:None

Contact Information
Durga Niraula
Los Angeles County
Internal Services
9150 E Imperial Hwy

Downey, CA 90242

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