San Mateo County District 5 voters pick a new county supervisor on Tuesday, Nov. 3, 2026: South San Francisco Vice Mayor Mark Nagales or Daly City Councilmember Juslyn Cabrera Manalo. The winner replaces Supervisor David Canepa.

Why it matters: District 5 covers parts of northern and eastern San Mateo County, according to Patch. Canepa is leaving roughly two years early, so the winner fills the rest of his term.

Why there's a special election

  • Canepa was elected in June as the county's next assessor-county clerk-recorder and chief elections officer, and he leaves the Board of Supervisors on Jan. 4, 2027, Redwood City Pulse reported.
  • The county charter requires a special election when a vacancy occurs before Oct. 16 of a term's third year.
  • Canepa filed a deferred resignation so the race could be consolidated with the Nov. 3 general election. He said he asked for that "to save the county money" and "with an eye toward increasing voter participation."

The candidates

  • Mark Nagales, vice mayor of South San Francisco.
  • Juslyn Cabrera Manalo, Daly City City Council member.

Also on San Mateo County ballots

County voters decide four charter amendments: Measure J on filling vacancies and Measure AA on civil rights, Measure U on independent redistricting and Measure L on extreme weather. Daly City voters also have a seven-way council race. Full list: Election 2026 guide.