California's 4th congressional district

California's 4th congressional district is a U.S. congressional district in California. The district is located in the northwestern part of the state, and includes all of Lake County and Napa County, most of Yolo County, and parts of Solano County and Sonoma County. Major cities in the district include Davis, Woodland, Napa, Vacaville, and most of Santa Rosa. The district is solidly Democratic, and is represented by Mike Thompson.

From 2013 to 2023, the district encompassed The Sierra from Truckee to the Sequoia National Forest, as well as a largely suburban area on the edge of the Sacramento Valley in southwestern Placer County. It consisted of Alpine, Amador, Calaveras, El Dorado, Mariposa, and Tuolumne counties plus most of Placer County and portions of Fresno, Madera, and Nevada counties. The district was represented by Republican Tom McClintock.