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.
Competitiveness In 2006, Republicans had 48 percent of voter registrations, Democrats had 30 percent, and Libertarians had roughly 5 percent., The Sacramento Bee, May 10, 2006 A Democratic congressional candidate nearly won the district in 2008, losing by only half a percentage point and less than 1,600 votes, indicating that the district was much more competitive than it appeared to be.
New district boundaries for the 2012 elections shifted the population center to the south and east. Registered Democrats and Independents/Decline to State voters in the new district area outnumber registered Republicans by 12%. However, Republicans, Independents/Decline to State, and small third parties outnumber Democrats well over a 2 to 1 ratio. There were 183,800 Republicans, 117,300 Democrats, and 97,200 others. In presidential elections, Donald Trump won the district in 2016 with 54% of the vote and won in 2020 with 53.7% of the vote. In the 2018 and 2020 elections, the Republican candidate won over 53% of the vote.California's 4th Congressional District Ballotpedia.
In the 2020 redistricting, the district was shifted again to the San Francisco Bay Area, covering the bulk of what had been the 5th District. It 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 new 4th district is solidly Democratic, and is represented by Mike Thompson.
Recent election results from statewide races 2023–2027 boundaries Year Office Results2008 PresidentObama 67% - 32%2010 GovernorBrown 59% - 36% Lt. GovernorNewsom 57% - 34% Secretary of StateBowen 58% - 33% Attorney GeneralHarris 51% - 39% TreasurerLockyer 61% - 31% ControllerChiang 61% - 29%2012 PresidentObama 66% - 34%2014 GovernorBrown 68% - 32%2016 PresidentClinton 64% - 29%2018 GovernorNewsom 65% - 35% Attorney GeneralBecerra 66% - 34%2020 PresidentBiden 67% - 30%2022 Senate (Reg.)Padilla 66% - 34% GovernorNewsom 63% - 37% Lt. GovernorKounalakis 65% - 35% Secretary of StateWeber 65% - 35% Attorney GeneralBonta 64% - 36% TreasurerMa 64% - 36% ControllerCohen 61% - 39%2024 PresidentHarris 64% - 33% Senate (Reg.)Schiff 64% - 36%
Composition County Code County Seat Population 33 Lake Lakeport 68,878 55 Napa Napa 133,21695SolanoFairfield449,21897SonomaSanta Rosa481,812 113 Yolo Woodland 220,544 Under the 2020 redistricting, California's 4th congressional district encompasses Lake, Napa, and Yolo Counties, and parts of Sonoma and Solano Counties. The area in Sonoma County includes the cities of Santa Rosa, Rohnert Park, Sonoma, Petaluma, and Cotati; and the census-designated places Boyes Hot Spring, El Verano, Penngrove, Sonoma State University, Kenwood, Glen Ellen, Eldridge, Fetters Hot Springs-Agua Caliente, and Temelec. The area in Solano County includes the cities of Vacaville, Dixon, and Rio Vista; and the census-designated places Hartley and Allendale.
Sonoma County is split between this district and the 2nd district. They are partitioned by Petaluma River, Highway 116, Redwood Highway, Robber Rd, Petersen Rd, Llano Rd, S Wright Rd, W College Ave, Jennings Ave, Administration Dr, Bicentennial Way, Cleveland Ave, Old Redwood Highway, Cross Creek Rd, Sonoma Highway, and Sonoma Creek.
Solano County is split between this district and the 8th district. They are partitioned by Soda Springs Rd, Union Pacific, Alamo Dr, Leisure Town Rd, Hawkins Rd, Bay Area Exxextric, Shilo Rd, Collinsville Rd, and Montezuma Slough.
Cities and CDPs with 10,000 or more people Santa Rosa – 178,127 Vacaville – 102,386 Napa – 77,480 Davis – 66,850 Woodland – 61,032 Petaluma – 59,776 West Sacramento – 53,519 Rohnert Park – 44,390 American Canyon – 21,837 Dixon – 18,988 Clearlake – 16,685 Sonoma – 11,024 Rio Vista – 10,217
2,500 – 10,000 people University of California, Davis – 8,525 Cotati – 7,584 Winters – 7,195 Hidden Valley Lake – 6,235 Boyes Hot Springs – 6,215 St. Helena – 5,438 Calistoga – 5,228 Lakeport – 5,026 Penngrove – 4,172 Fetters Hot Springs-Agua Caliente – 4,144 El Verano – 3,867 Yountville – 3,436 Kelseyville – 3,382 Clearlake Riviera (Kelseyville Riviera) – 3,410 North Lakeport – 3,314 Esparto – 3,108 Lucerne – 3,067 Esparto – 2,877 Nice – 2,731 Sonoma State University – 2,679 Angwin – 2,633 Clearlake Oaks – 2,551 Hartley – 2,510
Future composition Beginning with the 2026 election, the 4th district will consist of the following counties:
Colusa Lake (part) Napa Placer (part) Sacramento (part) Sonoma (part) Sutter Yolo (part) Yuba
List of members representing the district Member Party Dates Congress Electoral historyCounties District created March 4, 1873 Sherman Otis Houghton Republican March 4, 1873 –March 3, 1875 Redistricted from the and re-elected in 1872.lost re-election. Fresno, Inyo, Kern, Los Angeles, Mariposa, Merced, Mono, Monterey, San Bernardino, San Diego, San Luis Obispo, San Mateo, Santa Barbara, Santa Clara, Santa Cruz, Stanislaus, Tulare, Ventura Peter D. Wigginton Democratic March 4, 1875 –March 3, 1877 Elected in 1875.Retired. Romualdo Pacheco Republican March 4, 1877 –February 7, 1878 Lost contested election. Peter D. Wigginton Democratic February 7, 1878 –March 3, 1879 Won contested election.Retired. Romualdo Pacheco Republican March 4, 1879 –March 3, 1883 Elected in 1879.Re-elected in 1880.Retired. Pleasant B. Tully Democratic March 4, 1883 –March 3, 1885 Elected in 1882.Retired. San Francisco William W. Morrow Republican March 4, 1885 –March 3, 1891 Elected in 1884.Re-elected in 1886.Re-elected in 1888.Retired. John T. Cutting Republican March 4, 1891 –March 3, 1893 Elected in 1890.Retired. James G. Maguire Democratic March 4, 1893 –March 3, 1899 Elected in 1892.Re-elected in 1894.Re-elected in 1896.Retired. Julius Kahn Republican March 4, 1899 –March 3, 1903 Elected in 1898.Re-elected in 1900.Lost re-election. Edward J. Livernash Democratic/Union Labor March 4, 1903 –March 3, 1905 Elected in 1902.Lost re-election. Julius Kahn Republican March 4, 1905 –December 18, 1924 Elected in 1904.Re-elected in 1906.Re-elected in 1908.Re-elected in 1910.Re-elected in 1912.Re-elected in 1914.Re-elected in 1916.Re-elected in 1918.Re-elected in 1920.Re-elected in 1922.Re-elected in 1924.Died. Vacant December 18, 1924 –February 17, 1925 Florence Prag Kahn Republican February 17, 1925 –January 3, 1937 Elected to finish husband's term.Re-elected in 1926.Re-elected in 1928.Re-elected in 1930.Re-elected in 1932.Re-elected in 1934.Lost re-election. Franck R. Havenner Progressive January 3, 1937 –December 30, 1937 Elected in 1936.Re-elected in 1938.Lost re-election. Democratic December 30, 1937 –January 3, 1941 Thomas Rolph Republican January 3, 1941 –January 3, 1945 Elected in 1940.Re-elected in 1942.Lost re-election. Franck R. Havenner Democratic January 3, 1945 –January 3, 1953 Elected in 1944.Re-elected in 1946.Re-elected in 1948.Re-elected in 1950.Lost re-election. William S. Mailliard Republican January 3, 1953 –January 3, 1963 Elected in 1952.Re-elected in 1954.Re-elected in 1956.Re-elected in 1958.Re-elected in 1960.Redistricted to the . Robert Leggett Democratic January 3, 1963 –January 3, 1979 Elected in 1962.Re-elected in 1964.Re-elected in 1966.Re-elected in 1968.Re-elected in 1970.Re-elected in 1972.Re-elected in 1974.Re-elected in 1976.Retired. 1963–1967Colusa, Glenn, Lake, Solano, Sutter, Yolo, Yuba 1967–1973Colusa, Glenn, Lake, Sacramento (outside the city), Solano, Sutter, Yolo, Yuba 1973–1975Colusa, Glenn, Solano, southwestern Sacramento, Sutter, Yolo, Yuba 1975–1983Colusa, western Sacramento, Solano, Sutter, Yolo Vic Fazio Democratic January 3, 1979 –January 3, 1993 Elected in 1978.Re-elected in 1980.Re-elected in 1982.Re-elected in 1984.Re-elected in 1986.Re-elected in 1988.Re-elected in 1990.Redistricted to the . 1983–1993Sacramento (outside the city), Solano, Yolo John Doolittle Republican January 3, 1993 –January 3, 2009 Redistricted from the and re-elected in 1992.Re-elected in 1994.Re-elected in 1996.Re-elected in 1998.Re-elected in 2000.Re-elected in 2002.Re-elected in 2004.Re-elected in 2006.Retired. 1993–2003Alpine, Amador, Calaveras, El Dorado, Mono, Placer, northeastern Sacramento, Tuolumne 2003–2013Eastern Butte, El Dorado, Lassen, Modoc, Nevada, Placer, Plumas, Sacramento (Orangevale), Sierra Tom McClintock Republican January 3, 2009 –January 3, 2023 Elected in 2008.Re-elected in 2010.Re-elected in 2012.Re-elected in 2014.Re-elected in 2016.Re-elected in 2018.Re-elected in 2020.Redistricted to the . 2013–2023Eastern central California including Lake Tahoe, Roseville, and Yosemite National Park Mike Thompson Democratic January 3, 2023 – present Redistricted from the and re-elected in 2022.Re-elected in 2024.2023–presentLake, Napa, most of Yolo, parts of Solano and Sonoma
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In 2018, six Democratic candidates filed statements of candidacy with the Federal Election Commission (FEC). They were, in alphabetical order by last name: Regina Bateson; Roza Calderon; Richard Martin; Robert Lawton; Jessica Morse ; and Rochelle Wilcox. Martin and Wilcox dropped out of the race, with Wilcox endorsing Morse in February.
Retired Air Force Lieutenant Colonel Charlie Brown, who was the Democratic nominee for this seat in 2006 and 2008, was "seriously considering" running in 2018, but decided in June 2017 against a third campaign. In January 2018, Brown endorsed Morse for the nomination. Bob Derlet, the Democratic nominee in 2016, also endorsed Morse in January.
On the Republican side, McClintock had one challenger, Mitchell Kendrick White , who filed with the FEC in January.