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 new 4th district is solidly Democratic, and is represented by Mike Thompson.^[1]

California's 4th congressional district
Interactive map of district boundaries since 2023 (Used in the 2022 elections)
Representative	Mike Thompson D–St. Helena
Population (2022)	765,203[1]
Median household income	$87,319[2]
Ethnicity	51.3% White 31.4% Hispanic 7.6% Asian 5.3% Two or more races 2.8% Black 1.6% other
Cook PVI	D+17[3]

From 2013 to 2023, the district encompassed the Sierras 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.^[4]

In 2006, Republicans had 48 percent of voter registrations, Democrats had 30 percent, and Libertarians had roughly 5 percent.^[5] 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.^[6] 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.^[7]

In the 2020 redistricting, the district was shifted again to the San Francisco Bay Area. 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.^[1] The Solano County portion including Vacaville and Dixon have consistently been more conservative as evidenced by the 2022 midterms, voters in Congressional District 4 favored the Republican candidate 50.3% to 49.7%.^[8]

Election results from statewide races
Year	Office	Results
1992	President	Bush (R) 40.7 - 33.9%
	Senator	Herschensohn (R) 50.0 - 39.7%
	Senator	Feinstein (D) 46.0 - 45.2%
1994	Governor	Wilson (R) 66.4 - 29.0%
	Senator
1996	President	Dole (R) 51.3 - 37.8%
1998	Governor
	Senator
2000	President[9]	Bush (R) 58.1 - 36.9%
	Senator[10]	Campbell (R) 51.1 - 41.8%
2002	Governor[11]	Simon (R) 58.5 - 30.6%
2003	Recall[12][13]	Y Yes 70.4 - 29.6%
		Schwarzenegger (R) 60.6 - 17.6%
2004	President[14]	Bush (R) 61.3 - 37.4%
	Senator[15]	Jones (R) 55.6 - 40.1%
2006	Governor[16]	Schwarzenegger (R) 72.2 - 22.8%
	Senator[17]	Mountjoy (R) 50.2 - 44.3%
2008	President[18]	McCain (R) 54.0 - 43.8%
2010	Governor[19]	Whitman (R) 55.3 - 39.3%
	Senator[20]	Fiorina (R) 59.5 - 33.7%
2012	President	Romney (R) 57.9 - 39.5%
	Senator	Emken (R) 58.5 - 41.5%
2014	Governor	Kashkari (R) 55.1 - 44.9%
2016	President	Trump (R) 54.0 - 39.3%
	Senator	Harris (D) 63.3 - 36.7%
2018	Governor	Cox (R) 59.5 - 40.5%
	Senator	de Leon (D) 54.7 - 45.3%
2020	President	Trump (R) 53.7 - 43.9%
2021	Recall[21]	Y Yes 58.9 - 41.1%
2022	Governor[22]	Newsom (D) 63.3 - 36.7%
	Senator	Padilla (D) 65.7 - 34.3%

#	County	Seat	Population
33	Lake	Lakeport	68,766
55	Napa	Napa	136,207
113	Yolo	Woodland	216,986

As of 2023, California's 4th congressional district encompasses Lake, Napa, and Yolo Counties, and parts of Sonoma and Solano Counties.

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. The 4th district takes in the cities of Santa Rosa, Rohnert Park, Sonoma, and Cotati, the town of Windsor, and the census-designated places of Boyes Hot Spring, Roseland, El Verano, Penngrove.

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. The 4th district takes in the city of Vacaville, Dixon, Rio Vista, and the census-designated place of Hartley.

Cities & CDP with 10,000 or more people

• Vacaville - 102,386
• Napa - 77,480
• Davis - 66,850
• Woodland - 55,229
• West Sacramento - 53,519
• American Canyon - 21,837
• Dixon - 18,974
• Clearlake - 15,134

2,500-10,000 people

• University of California, Davis - 6,805
• Hidden Valley Lake - 6,243
• Winters - 6,616
• St. Helena - 5,939
• Calistoga - 5,266
• Lakeport - 4,799
• North Lakeport - 3,514
• Angwin - 3,179
• Yountville - 2,984
• Kelseyville - 2,923
• Clearlake Riviera - 2,850
• Esparto - 2,877

Member	Party	Dates	Cong ress	Electoral history	Counties
District created March 4, 1873
Sherman Otis Houghton (San Jose)	Republican	March 4, 1873 – March 3, 1875	43rd	Redistricted from the 1st district 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 (Merced)	Democratic	March 4, 1875 – March 3, 1877	44th	Elected in 1875. Retired.
Romualdo Pacheco (San Luis Obispo)	Republican	March 4, 1877 – February 7, 1878	45th	Lost contested election.
Peter D. Wigginton (Merced)	Democratic	February 7, 1878 – March 3, 1879		Won contested election. Retired.
Romualdo Pacheco (San Luis Obispo)	Republican	March 4, 1879 – March 3, 1883	46th 47th	Elected in 1879. Re-elected in 1880. Retired.
Pleasant B. Tully (Gilroy)	Democratic	March 4, 1883 – March 3, 1885	48th	Elected in 1882. Retired.	San Francisco
William W. Morrow (San Francisco)	Republican	March 4, 1885 – March 3, 1891	49th 50th 51st	Elected in 1884. Re-elected in 1886. Re-elected in 1888. Retired.
John T. Cutting (San Francisco)	Republican	March 4, 1891 – March 3, 1893	52nd	Elected in 1890. Retired.
James G. Maguire (San Francisco)	Democratic	March 4, 1893 – March 3, 1899	53rd 54th 55th	Elected in 1892. Re-elected in 1894. Re-elected in 1896. Lost re-election.
Julius Kahn (San Francisco)	Republican	March 4, 1899 – March 3, 1903	56th 57th	Elected in 1898. Re-elected in 1900. Lost re-election.
Edward J. Livernash (San Francisco)	Democratic/ Union Labor	March 4, 1903 – March 3, 1905	58th	Elected in 1902. Lost re-election.
Julius Kahn (San Francisco)	Republican	March 4, 1905 – December 18, 1924	59th 60th 61st 62nd 63rd 64th 65th 66th 67th 68th	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	68th
Florence Prag Kahn (San Francisco)	Republican	February 17, 1925 – January 3, 1937	68th 69th 70th 71st 72nd 73rd 74th	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 (San Francisco)	Progressive	January 3, 1937 – January 3, 1939	75th 76th	Elected in 1936. Re-elected in 1938. Lost re-election.
	Democratic	January 3, 1939 – January 3, 1941
Thomas Rolph (San Francisco)	Republican	January 3, 1941 – January 3, 1945	77th 78th	Elected in 1940. Re-elected in 1942. Lost re-election.
Franck R. Havenner (San Francisco)	Democratic	January 3, 1945 – January 3, 1953	79th 80th 81st 82nd	Elected in 1944. Re-elected in 1946. Re-elected in 1948. Re-elected in 1950. Lost re-election.
William S. Mailliard (San Francisco)	Republican	January 3, 1953 – January 3, 1963	83rd 84th 85th 86th 87th	Elected in 1952. Re-elected in 1954. Re-elected in 1956. Re-elected in 1958. Re-elected in 1960. Redistricted to the 6th district.
Robert Leggett (Vallejo)	Democratic	January 3, 1963 – January 3, 1979	88th 89th 90th 91st 92nd 93rd 94th 95th	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.	1963–1967 Colusa, Glenn, Lake, Solano, Sutter, Yolo, Yuba
					1967–1973 Colusa, Glenn, Lake, Sacramento (outside the city), Solano, Sutter, Yolo, Yuba
					1973–1975 Colusa, Glenn, Solano, southwestern Sacramento, Sutter, Yolo, Yuba
					1975–1983 Colusa, western Sacramento, Solano, Sutter, Yolo
Vic Fazio (West Sacramento)	Democratic	January 3, 1979 – January 3, 1993	96th 97th 98th 99th 100th 101st 102nd	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 3rd district.
					1983–1993 Sacramento (outside the city), Solano, Yolo
John Doolittle (Roseville)	Republican	January 3, 1993 – January 3, 2009	103rd 104th 105th 106th 107th 108th 109th 110th	Redistricted from the 14th district 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.	1993–2003 Alpine, Amador, Calaveras, El Dorado, Mono, Placer, northeastern Sacramento, Tuolumne
					2003–2013 Eastern Butte, El Dorado, Lassen, Modoc, Nevada, Placer, Plumas, Sacramento (Orangevale), Sierra
Tom McClintock (Elk Grove)	Republican	January 3, 2009 – January 3, 2023	111th 112th 113th 114th 115th 116th 117th	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 3rd district.
					2013–2023 Eastern central California including Lake Tahoe, Roseville, and Yosemite National Park
Mike Thompson (St. Helena)	Democratic	January 3, 2023 – present	118th	Redistricted from the 5th district and re-elected in 2022.	2023–present Lake, Napa, most of Yolo, parts of Solano and Sonoma

1872 • 1874 • 1876 • 1878 • 1880 • 1882 • 1884 • 1886 • 1888 • 1890 • 1892 • 1894 • 1896 • 1898 • 1900 • 1902 • 1904 • 1906 • 1908 • 1910 • 1912 • 1914 • 1916 • 1918 • 1920 • 1922 • 1924 • 1926 • 1928 • 1930 • 1932 • 1934 • 1936 • 1938 • 1940 • 1942 • 1944 • 1946 • 1948 • 1950 • 1952 • 1954 • 1956 • 1958 • 1960 • 1962 • 1964 • 1966 • 1968 • 1970 • 1972 • 1974 • 1976 • 1978 • 1980 • 1982 • 1984 • 1986 • 1988 • 1990 • 1992 • 1994 • 1996 • 1998 • 2000 • 2002 • 2004 • 2006 • 2008 • 2010 • 2012 • 2014 • 2016 • 2018 • 2020 • 2022

1872

1872 United States House of Representatives elections

Party		Candidate	Votes	%
	Republican	Sherman Otis Houghton (Incumbent)	10,391	53.5
	Democratic	Edward J. Kewen	9,012	46.5
Total votes			19,403	100.0
Turnout
	Republican hold

1874

1874 United States House of Representatives elections

Party		Candidate	Votes	%
	Democratic	Peter D. Wigginton	15,649	48.8
	Republican	Sherman Otis Houghton (Incumbent)	11,090	34.6
	Independent	J. S. Thompson	5,343	16.7
Total votes			32,082	100.0
Turnout
	Democratic gain from Republican

1876

1876 United States House of Representatives elections

Party		Candidate	Votes	%
	Republican	Romualdo Pacheco	19,104	50.0
	Democratic	Peter D. Wigginton (Incumbent)	19,103	50.0
Total votes			38,207	100.0
Turnout
	Republican gain from Democratic

1878

1878 United States House of Representatives elections

Party		Candidate	Votes	%
	Republican	Romualdo Pacheco	15,391	40.5
	Democratic	Wallace A. Leach	12,109	31.8
	Workingman's	James J. Ayres [23]	10,527	27.7
Total votes			38,027	100.0
Turnout
	Republican hold

1880

1880 United States House of Representatives elections

Party		Candidate	Votes	%
	Republican	Romualdo Pacheco (Incumbent)	17,768	45.8
	Democratic	Wallace A. Leach	17,577	45.3
	Greenback	J. F. Godfrey	3,435	8.9
Total votes			38,780	100.0
Turnout
	Republican hold

1882

1882 United States House of Representatives elections

Party		Candidate	Votes	%
	Democratic	Pleasant B. Tully	23,105	54.4
	Republican	George Lemuel Woods	18,387	43.3
	Populist	M. V. Wright	650	1.5
	Prohibition	Isaac Kinley	355	0.8
Total votes			42,497	100.0
Turnout
	Democratic gain from Republican

1884

1884 United States House of Representatives elections

Party		Candidate	Votes	%
	Republican	William W. Morrow	15,083	58.8
	Democratic	R. P. Hastings	10,422	40.6
	Populist	H. S. Fitch	123	0.5
	Prohibition	George Babcock	15	0.1
Total votes			25,643	100.0
Turnout
	Republican gain from Democratic

1886

1886 United States House of Representatives elections

Party		Candidate	Votes	%
	Republican	William W. Morrow (Incumbent)	11,413	48.6
	Democratic	Frank McCoppin	9,854	42.0
	Independent	Charles Allen Sumner	2,104	9.0
	Prohibition	Robert Thompson	84	0.4
Total votes			23,455	100.0
Turnout
	Republican hold

1888

1888 United States House of Representatives elections

Party		Candidate	Votes	%
	Republican	William W. Morrow (Incumbent)	14,217	50.8
	Democratic	Robert Ferral	13,624	48.6
	Socialist	Frank M. Pixley	173	0.6
Total votes			28,014	100.0
Turnout
	Republican hold

1890

1890 United States House of Representatives elections

Party		Candidate	Votes	%
	Republican	John Tyler Cutting	13,196	49.2
	Democratic	Robert Ferral	12,091	45.1
	Socialist	Thomas V. Cator	1,492	5.6
	Prohibition	Joseph Rowell	50	0.2
Total votes			26,829	100.0
Turnout
	Republican hold

1892

1892 United States House of Representatives elections

Party		Candidate	Votes	%
	Democratic	James G. Maguire	14,997	49.2
	Republican	Charles O. Alexander	13,226	43.4
	Populist	Edgar P. Burman	1,980	6.5
	Prohibition	Henry Collins	296	1.0
Total votes			30,499	100.0
Turnout
	Democratic gain from Republican

1894

1894 United States House of Representatives elections

Party		Candidate	Votes	%
	Democratic	James G. Maguire (Incumbent)	14,748	48.3
	Republican	Thomas B. Shannon	9,785	32.0
	Populist	B. K. Collier	5,627	18.4
	Prohibition	Joseph Rowell	388	1.3
Total votes			30,548	100.0
Turnout
	Democratic hold

1896