Primer: Redistricting in California

How it works, how the current system came to be, and what to know about Proposition 50.

With Proposition 50 — which would impact congressional redistricting until 2030 — on the November ballot, many Californians are wondering what the ballot measure would do and how redistricting works. This primer outlines California’s current redistricting system, traces how it developed through previous propositions, and explains the choice voters face in the upcoming special election on Proposition 50.

Every ten years after the census, the 435 seats in the U.S. House of Representative are reapportioned among the states, based on population, and new Congressional district boundaries are made. Lines are also redrawn for the California Assembly (80 seats), Senate (40 seats), and Board of Equalization (four seats plus the State Controller) based upon population shifts. When it comes time to draw and adopt new political maps, the debate often becomes fiercely contentious due to the maps’ long-lasting ramifications for political power in each of these houses.

Proposition 11 (2008)

Prior to 2008, the California Legislature drew district boundaries for itself, the Board of Equalization, and the state’s U.S. House seats. In 2008, California voters approved Proposition 11, which established the Citizens Redistricting Commission. This new commission was tasked with drawing the boundaries for state legislature districts and Board of Equalization districts.

The Citizens Redistricting Commission has 14 members: five Democrats, five Republicans, and four unaffiliated with either major party. There are criteria for eligibility, such as not having been a lobbyist or large political donor within the past 10 years. California voters may apply online to sit on the Commission. Three auditors from the Bureau of State Audits choose 120 applicants (40 Republican, 40 Democrat, and 40 unaffiliated) to interview. Following the interviews, the candidate pool is further reduced to 60 (20 from each of the three pools), then legislative leaders in the state Senate and Assembly may strike up to eight candidates from each pool. From the remaining applicants, the state auditor randomly selects eight candidates to be commissioners: three Democrats, three Republicans, and two unaffiliated. These eight commissioners select who fills the remaining seats by majority vote, drawing from the remaining applicants.

The Citizens Redistricting Commission must hear public comment on new map proposals, and to approve a new map, must have nine “yes” votes (at least three from Democrat members, three from Republican members, and three from other members). An approved plan is used for the next decade, with new commission members every ten years.

Proposition 11 also required state Senate districts to be composed of two adjacent Assembly districts, and for Board of Equalization districts of ten adjacent Senate districts.

Proposition 20 (2010)

In 2010, California voters passed Proposition 20, transferring U.S. House of Representatives redistricting in California to the Citizens Redistricting Commission. Thus, with Proposition 20 the Citizens Redistricting Commission was responsible for developing and approving political maps for the following political seats:

• California Assembly and Senate
• California Board of Equalization
• U.S. House of Representatives seats from California

Proposition 11 (2008) had required that “communities of interest” be maintained, without defining exactly what those were. Proposition 20 defines a community of interest as “a contiguous population which shares common social and economic interests that should be included within a single district for purposes of its effective and fair representation.”

Opposition to the Citizens Redistricting Commission

In the 2010 election, Proposition 20 had a competing proposal, Proposition 27, that would have accomplished the opposite result. Proposition 27 would have (1) disbanded the Citizens Redistricting Commission (2) returned all map-making authority back to the legislature for state Assembly, state Senate and state Board of Equalization districts, and (3) retained the state legislature’s authority over U.S. House of Representatives districts for California seats. Voters rejected Proposition 27, opting to keep the Citizens Redistricting Commission and Proposition 11’s reforms in place.

Proposition 50 (November 4, 2025)

This November, California voters are again tasked with deciding redistricting authority, with a similar proposal to Proposition 27 from 2010. Proposition 50 would shift control of congressional redistricting from the Citizens Redistricting Commission back to the state legislature from 2026 to 2030.

If California voters approve Proposition 50, the next congressional map the state adopts will be drawn by the state legislature, and used until the 2030 census when new maps are drawn. If they reject it, the Citizens Redistricting Commission maps will remain in place.