Profile Picture Mark Greninger

created Apr 18 2017

updated May 23 2022


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 are now called ‘Countywide Statistical Areas’ (as of July 2016).
To learn more about this project, click on this link to go to the project page.
Download the data
The dataset below is the current final draft of the BASA boundaries. As of this December 2015 we are developing the language to have them approved by the Board of Supervisors.
BOS_COUNTYWIDE_STATISTICAL_AREAS_20170118 (zipped shapefile)
Purpose of the data
Communities are one of the most complex geographic issues in the County of Los Angeles, due to historical narratives, perceptions of value, intense public interest, and shifts over time. The County has a need to establish a consistent geographic reporting base that will enable statistics and information to reported to the Board, that attempts to represent all of the interactions but is primarily focused on reporting.
Historically, County departments provide statistics and reports to the Board for Unincorporated Areas of the Los Angeles County based upon inconsistent geographic boundaries and names. These disparities impacted the ability of the Board to work with communities and residents to communicate priorities, service levels, and effect positive change in the County.
Reporting of statistics by County departments to Board offices by consistent geographic areas will simplify reporting, improve internal and external communications, and support better decision making. Leveraging boundaries used by the United States Census Bureau will enable demographic information to be used as part of County reporting. To download the geographic building blocks for this dataset, which also provide city boundaries each year since 2010 along with relevant Census block group and tract boundaries, go to the Split 2010 Block Group/City – BASA page.
The Geographic Information Officer and the LA County Enterprise GIS group worked with the Los Angeles County Board of Supervisors Unincorporated Area and Field Deputies to establish names that reflect as best as possible the general name preferences of residents and historical names of areas. A Board Motion will establish these area names as “Board Approved.” BASAs differ from the more informal “Community” geographies because:
They are primarily focused on broad statistics and reporting, not mapping of communities.
They represent board approved geographies comprised of Census block groups split by cities.
They must cover the entire unincorporated County
There can be no holes or overlapping areas
Naming Conventions
BASAs were be named according to the following recommended naming conventions:
All names will be assumed to begin with “Unincorporated” (e.g. Unincorporated El Camino Village). They will not be part of the Statistical Geography Name (so the name of the Statistical Area would be “El Camino Village”).
Names will not contain “Island” – beginning each name with “Unincorporated” will distinguish an area from any surrounding cities. There may be one or more exceptions for certain small areas (e.g. “Bandini Islands”)
A forward slash implies an undetermined boundary between two areas within a statistical geography (e.g. Westfield/Academy Hills or View Park/Windsor Hills)
Certain established names may include hyphens (e.g. Florence-Firestone)
Aliases may be defined in parentheses (e.g. Unincorporated Long Beach (Bonner/Carson Park))
Geographic Base
The BASAs were created using Census Block Groups split by cities (e.g. “Split Block Groups”) as a geographic building block. This allows users to leverage the rich information provided by the US Census Bureau to better report statistics, including rates from the decennial census and population estimates. LA County aligned a large number of block group boundaries to city boundaries where those boundaries were incorrectly mis-aligned by the Census Bureau – this file is accurate to the legal city boundary.
In the City of Los Angeles, the LA City Neighborhood file was overlaid on the Block Groups and boundaries assigned using the centroid of the block group – therefore, while the names of the BASAs in LA City match the neighborhood file, the boundaries are not the same.

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GIS Data
communities, cities, statistics, demographics
Licensing and Attribution
Data Provided By
LA County
Source Link
Public Domain
Dataset Update Frequency
Update Frequency
As available
Department Name
Enterprise GIS
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