Analyzing California’s Adjusted Redistricting Data

Overview

California uses adjusted (or modified) data for US congressional and state legislative redistricting.

• 39,538,223 total population in the original PL file
• 39,523,437 total population in the adjusted PL file
• -14,786 total population difference between the two

Even in states where where the total population is unchanged, the distribution of population within the state can be affected.

To give you a sense for how these population shifts affect California’s redistricting, the average district sizes in California are:

• 494,042 people per state House district
• 988,085 people per state Senate district
• 760,066 people per Congressional district

The dataset used to create this report is the official redistricting dataset.

County Level Analysis

See the appendix for a detailed breakdown of county level population changes.

Block Level Analysis

In general, the changes in block population are not uniform: most blocks are unaffected by modification, while a handful of blocks lose a large amount of population that goes to a larger number of blocks in smaller quantities.

• 519,723 census blocks in California
• 438,126 census blocks have the same population following modification
• 81,455 census blocks gained population following modification
• 142 census blocks lost population following modification (Of the 142 census blocks that lost population following reallocation, 142 contained facilities according to our analysis conducted with PPI data.)

Official Language

The official language for California’s modification is:

Consistent with Section 2025, the Legislature hereby requests the Citizens Redistricting Commission to deem each incarcerated person as residing at that person’s last known place of residence, rather than at the institution of that person’s incarceration, and to use the information furnished to it pursuant to subdivision (a) in carrying out its redistricting responsibilities under Article XXI of the California Constitution. The Legislature also requests the Citizens Redistricting Commission to do all of the following when it uses information regarding inmates that is furnished pursuant to this section: (1) Deem an inmate incarcerated in a state correctional facility for whom the last known place of residence is either outside California or cannot be determined, or an inmate in federal custody in a facility within California, to reside at an unknown geographical location in the state and exclude the inmate from the population count for any district, ward, or precinct. (2) Adjust race and ethnicity data in districts, wards, and precincts that contain prisons in a manner that reflects reductions in the local population as inmates are included in the population count of the district, ward, or precinct of their last known place of residence and, to the extent practicable, those deemed to reside at an unknown geographic location. [More on defiining last place of residence]