San Mateo County voters will decide Measure U on Nov. 3, 2026, a county charter amendment that would hand the job of drawing the five supervisorial district lines to an independent redistricting commission instead of the Board of Supervisors. The board voted to put it on the ballot, and it needs a simple majority to pass. It is one of four county charter amendments on this year's ballot. See all local races and measures on our Bay Area Election 2026 guide.
How district lines are drawn now
Every 10 years, after the federal census, county supervisorial districts are redrawn so each has roughly the same population. Under Section 202 of the county charter, the districts are set by ordinance, which means the Board of Supervisors itself adopts the final map, according to the county counsel's impartial analysis. KQED's voter guide notes the board currently does that based on the recommendation of a 15-member advisory panel, but the supervisors have the last word.
What a yes vote does
A yes vote rewrites Section 202 and adds a new Section 202.1 requiring that the districts be redrawn after each decennial census by an "independent redistricting commission" as defined in the California Elections Code. State law defines that as a body other than the board itself that is empowered to adopt the boundaries, and state law limits who can serve on it to keep it independent. The commission, not the supervisors, would adopt the final map. The first maps under the new rule would come after the 2030 census.
The measure leaves the rest of Section 202 alone. Supervisors would still be elected by district, still have to live in the district they represent, and still serve four-year terms with a limit of three consecutive terms.
What a no vote does
A no vote keeps the current system, with the Board of Supervisors adopting district boundaries by ordinance. The impartial analysis points out that state law also lets a county create an independent commission by resolution or ordinance, so a no vote would not permanently rule one out. It would just keep the requirement out of the charter.
Who is for and against
The ballot argument in favor is signed by Supervisors Jackie Speier (District 1) and Lisa Gauthier (District 4), Linda Jansen, president of the League of Women Voters of North and Central San Mateo County, and Lucia Tedesco, president of the League of Women Voters of South San Mateo County. KQED also lists Supervisor Noelia Corzo as a supporter. "Vote YES on Measure U to ensure that voters choose their representatives—not the other way around," the argument says. It says the board has, "most recently, overridden the recommendations of citizen members of a redistricting commission," and calls final control by elected officials "an inherent conflict of interest."
The argument notes that any commission must follow California's ranked map-drawing criteria: equal population first, then keeping communities of interest together, keeping cities and census tracts whole where practical, and drawing contiguous, reasonably compact districts. No argument against Measure U was submitted, and KQED lists no organized opposition.
The other county charter questions
Measure U shares the county ballot with Measure J (more time to fill vacancies in elected county offices other than supervisor), Measure AA (an affirmation of rights) and Measure L on extreme weather resilience. In the city of San Mateo, Measure F asks a separate question about the city's own charter and district elections.
As of 5 p.m. Oct. 19, the county elections office reported about 449,000 registered voters and 38,505 vote-by-mail ballots already received.