California's 4th Congressional District is represented by Mike Thompson (Democrat), who has served in the House since 1999 and has represented this district since redistricting in 2023. Thompson has an overall VoteSee report card grade of B, voted in 100% of roll-call votes on bills this Congress, and votes with the Democratic majority 96% of the time. The district includes Santa Rosa, Vacaville, and Napa. It takes in all or part of 5 counties; the most populous parts are in Sonoma County and Yolo County. About 764,000 people live in the district, and the median household income is $97,540.
Mike Thompson (Democrat) has served in the House since 1999 and has represented California's 4th Congressional District since redistricting in 2023.
See Mike Thompson's full voting record and issue positions →
Incumbent Mike Thompson is running for re-election. 2 candidates were on the Nov 3, 2026 ballot.
California uses a top-two primary, so the two November candidates can be from the same party.
Polls: No public polls
Source: American Community Survey 2020–2024 5-year estimates, 119th Congress boundaries.
Members of Congress who previously represented California's 4th Congressional District. District lines are redrawn after each census, so earlier members may have represented a different area under this number.
California's 4th Congressional District covers 3,780 square miles of land. Boundaries are for the current (119th) Congress.