This data is the product of 2020 census tracts split by 2023 incoporated city boundaries and unincorpoerated community/countywide statistical areas (CSA) boundaries. The census tract boundaries have been altered and aligned where necessary with legal city boundaries and unincorporated areas, including along shoreline/coastal areas. This data is also known as the Split Tract data. This data can be used to estimate population changes over time.

Census Tract:

Every 10 years the Census Bureau counts the population of the United States as mandated by Constitution. The Census Bureau (http://www.census.gov/)released 2020 geographic boundaries data including census tracts for the analysis and mapping of demographic information across the United States.

City Boundary:

City Boundary data is the base map information for the County of Los Angeles. These City Boundaries are based on the Los Angeles County Seamless Cadastral Landbase. The Landbase is jointly maintained by the Los Angeles County Assessor and the Los Angeles County Department of Public Works (DPW). This layer represents current city boundaries within Los Angeles County. The DPW provides the most current shapefiles representing city boundaries and city annexations. True, legal boundaries are only determined on the ground by surveyors licensed in the State of California.

Countywide Statistical Areas (CSA):

The countywide Statistical Area (CSA) was defined to provide a common geographic boundary for reporting departmental statistics for unincorporated areas and incorporated Los Angeles city to the Board of Supervisors. The CSA boundary and CSA names are established by the CIO and the LA County Enterprise GIS group worked with the Los Angeles County Board of Supervisors Unincorporated Area and Field Deputies that reflect as best as possible the general name preferences of residents and historical names of areas. This data is primarily focused on broad statistics and reporting, not mapping of communities. This data is not designed to perfectly represent communities, nor jurisdictional boundaries such as Angeles National Forest. CSA represent board approved geographies comprised of Census block groups split by cities.

Data Field:

CT20FIP23CSA: ID field (combination of 2020 census tract number, 2023 city FIP code and CSA name)

CT20: 2020 Census Tract

FIP23: FIP code for legal city

CITY: Legal City Name (as of July 1, 2023)

CSA: Countywide Statistical Area (CSA) and Los Angeles City neighborhood names

How this data created?

This polygon data is created by intersecting 2020 census tract polygons, LA Country City neighborhood polygons and Countywide Statistical Areas (CSA) data polygon. The resulting polygon boundary aligned and matched with the legal city boundary whenever possible.

Updates:

1. 2023 July: The major updates include 2022 November Santa Clarita City annexation and Kinneloa Mesa community (previously it was a part of Unincorporated East Pasdena). This data also aligns with current city boundary along LA County shoreline areas.