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Analyzing California’s Adjusted Redistricting Data

Used for US congressional and state legislative redistricting

Full Report

The expanded report provides a detailed breakdown of the PL 94-171 data as released by the Census Bureau, compared to the reallocated, or adjusted data, provided by the state’s official redistricting body.

Specifically, this report details the differences in total population by census block, block group, tract, county, and state before and after reallocation. In states where comparisons are possible, these population differences are broken down by race and ethnicity.



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.

California's Adjusted Data Population Changes by County with Facility Locations

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.)
Population Change Number of Blocks
Gained 100+ 0
Gained 51-100 0
Gained 11-50 86
Gained 6-10 962
Gained 1-5 80,407
No Change 438,126
Lost 1-5 7
Lost 6-10 12
Lost 11-50 18
Lost 51-100 34
Lost 100+ 71

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]


County Population Change
Los Angeles 33,917
Orange 6,021
Santa Clara 3,881
San Diego 3,628
Contra Costa 2,142
Tulare 1,939
Stanislaus 1,852
Ventura 1,547
Alameda 1,115
Shasta 1,044
San Francisco 1,028
San Mateo 975
Butte 917
Sonoma 850
Placer 568
Yolo 519
Santa Cruz 491
Yuba 418
Humboldt 347
Sutter 293
Napa 279
El Dorado 272
Lake 238
Tehama 144
Siskiyou 131
San Benito 129
Colusa 59
Plumas 49
Nevada 43
Mendocino 23
Mono 22
Calaveras 14
Sierra 8
Alpine 3
Glenn -1
Trinity -11
Modoc -27
Mariposa -37
Inyo -53
Merced -103
Fresno -128
Sacramento -171
Riverside -747
San Bernardino -1,502
Santa Barbara -1,525
San Joaquin -1,920
Del Norte -2,603
Tuolumne -2,612
San Luis Obispo -3,208
Marin -3,766
Amador -3,882
Monterey -4,375
Madera -5,142
Solano -5,634
Imperial -6,076
Lassen -7,444
Kings -12,164
Kern -16,561