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CalEnviroScreen 3.0

In January 2017, The California Office of Environmental Health Hazard Assessment (OEHHA), on behalf of the California Environmental Protection Agency (CalEPA) released the latest version of CalEnviroScreen. Below is a brief description from their website. On their website you will be able to view the data with interactive maps, read the report in […]

Countywide Statistical Areas (formerly called Board Approved Statistical Areas) – Final Draft

Countywide Statistical Area (formerly called Board Approved Statistical Areas) provide a common geographic boundary for reporting departmental statistics for unincorporated areas to the Board of Supervisors. They are not designed to perfectly represent communities, nor jurisdictional boundaries such as the Angeles National Forest. References below might still be for BASA – but they […]


Census Designated Places (CDPs) are the statistical counterparts of incorporated places, and are delineated to provide data for settled concentrations of population that are identifiable by name but are not legally incorporated under the laws of the state in which they are located.

The boundaries usually are defined in cooperation with local or tribal officials […]


A census block is the smallest geographic unit used by the United States Census Bureau for tabulation of 100-percent data (data collected from all houses, rather than a sample of houses).

Blocks are typically bounded by streets, roads or creeks. In cities, a census block may correspond to a city block, but in rural areas […]


Block Groups (BGs) are statistical divisions of census tracts, are generally defined to contain between 600 and 3,000 people, and are used to present data and control block numbering. A block group consists of clusters of blocks within the same census tract.

IMPORTANT! This post includes the 2012 Census Geography Update, which merged Tracts 1370.00 […]

US Census Summary File 1 (2010)

These Summary File 1 tables provide the most detailed counts available so far from the 2010 Census, including cross-tabulations of age, sex, households, families, relationship to householder, housing units, detailed race and Hispanic or Latino origin groups, and group quarters at the census tract level.

Census Bureau Releases New Local-Level Demographic Information from 2010 Census […]

Split 2010 Block Group/City – Community Statistical Area (formerly BASA)

This dataset contains 2010 Block Groups, updated to improve geographic accuracy, split by City boundaries for each year since 2010. It is a foundation-level dataset that is used to create many other datasets and reporting within the County, including:

Legal City Boundaries Census Block Group and Tract Boundaries – which is used to […]

Public GIS Mapping Services

We are making a number of our GIS data layers available as public mapping services based upon ESRI’s ArcGIS Server technologies at this URL ( More details on each service will follow as we have the time to describe them, but generally they include GIS data that can be downloaded from […]

2010 Census Tracts (Spatial View)

This dataset is a spatial view and contains 2010 census tracts boundaries with the following attributes: P001, P003, P004, P005, P012, P014, P016, P017, P028, PCT 012, H0001, H003, H004, H005, H010, H013, MEDHINC, and age.

For Census technical documentation, go to

2010 Census Tracts (Median Household Income)

For mapping 2010 census tracts by median household income in the County of Los Angeles. The dataset was downloaded from For Census technical documentation, go to

2010 Census Tracts (Sex by Age)

This feature class shows 2010 Census Tracts (Sex by Age only) for Los Angeles County geographic area. The dataset was downloaded from

For Census technical documentation, go to

2010 Census Blocks (Sex by Age)

This feature class shows 2010 Census Blocks (Sex by Age) for Los Angeles County geographic area. The dataset was downloaded from and additional administrative boundary information was appended to the dataset.

For Census technical documentation, go to


Population and Poverty Estimates

County of Los Angeles had loaded numerous population and poverty estimates at either the Census Tract level or Census Tract-City split areas by age, gender, and/or race-ethnicity into the eGIS_Demographic database and the internal networked drive (members\Demography folder). These datasets are proprietary estimates acquired by Los Angeles County for internal analysis. County departments and agencies […]

Urban,Suburban and Rural designations by grid

Download the shapefile here: Urban Suburban Rural (zipped shapefile).

This layer was developed by the Fire Department to use in our annual reporting to the state. We must report total incidents by Urban,Suburban, and Rural. Using the State of California formula for urban,suburban was found to be not applicable to Los Angeles […]

California Spatial Information Library (CaSIL)

The Cal-Atlas site facilitates the coordinated and sustainable development, maintenance, licensing and sharing of geospatial data and web map services by California government agencies, partners and stakeholders. California government agencies work with the California GIS Council, regional GIS collaboratives and the broader California GIS community to define the data architecture, systems, standards, agreements and processes […]

Census Data and Boundaries (Historic)


The National Historical Geographic Information System (NHGIS) website recently is an incredibly valuable tool for historic demographics information. You just need to register.

From their site:

The National Historical Geographic Information System (NHGIS) provides, free of charge, aggregate census data and GIS-compatible boundary files for the United States […]

Census Blocks (2010)

Census Geography Background

The Census Bureau ( 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 […]

Census Tracts (2010)


IMPORTANT! It has been updated to the 2012 Census Geography Update, which merged Tracts 1370.00 and 9304.01 into the combined tract 1370.00. So the CT10 field actually reflects the 2012 Census update, which is used for all population products.

Census Geography Background

The Census Bureau ( maintains geographic boundaries […]

Census Cartographic Boundary Files

We do not have this data; but since we get a lot of requests for census tracts or other census data for our County, it seems logical to have a link here. This data is available from the US Census Bureau. 2010 data is not yet available.

Here’s the link to their download page: