Districts in California geographically divide the U.S. state into overlapping regions for political and administrative purposes.
From the founding of the state until 2008, the responsibility of redrawing the state's Congressional, Assembly, Senate, and Board of Equalization districts had been exercised by the California state legislature.
In November 2008, California voters passed Proposition 11, the Voters FIRST Act, which took political redistricting responsibility away from the state legislature and instead established a 14-member statewide redistricting commission composed of five Republicans, five Democrats, and four not affiliated with either of those two parties but registered with another party or as decline-to-state. The California Citizens Redistricting Commission was initially charged with updating the state assembly, senate, and Board of Equalization district boundaries starting with the 2010 census. Another initiative, Proposition 20, passed in 2010, expanded the Commission responsibilities to also include the state Congressional districts.
California is divided into 53 Congressional districts.
California is divided into 40 State Senate districts, each of which elects a senator to the State Senate. Twice the size of an Assembly district, each senate district contains about 931,000 people. The combined Senate roster is available from senate.ca.gov/senators. The members of the California Senate Republican caucus are listed at cssrc.us/senators.aspx.
Prior to 1968, state senate districts were restricted such that one county could only hold at most one seat. This led to the situation of Los Angeles County, with 6 million residents as of 1968, receiving 600 times less representation than residents of Alpine County and Calaveras County, some of California's least populous counties. The Reynolds v. Sims decision by the United States Supreme Court compelled all states to draw up districts that were apportioned by population rather than geography. As such, boundaries were changed such that equal representation was provided.
California is divided into 80 State Assembly districts, each of which elects a member to the State Assembly. Each assembly district contains about 466,000 people. Each Assembly member is limited to three terms by a referendum passed by California voters. In March 2008, Proposition 93 unsuccessfully attempted to change term limits to a maximum of twelve years or six terms instead of three.
The California Court of Appeal is divided into six appellate districts, based on geography. Some of the appellate districts are further divided into Divisions.
The California Court of Appeal for the First District is located in San Francisco. Its jurisdiction is over the following counties: Alameda, Contra Costa, Del Norte, Humboldt, Lake, Marin, Mendocino, Napa, San Francisco, San Mateo, Solano, and Sonoma. It is divided into five non-geographical divisions with four justices each.
The California Court of Appeal for the Second District has its main courthouse in Los Angeles and the secondary courthouse, hosting Division Six, in Ventura. Division Six handles appeals from San Luis Obispo, Santa Barbara, and Ventura Counties, while Divisions One through Five, Seven, and Eight handle appeals from Los Angeles County. Each division has four justices.
The California Court of Appeal for the Third District is located in Sacramento. Its jurisdiction is over the following counties: Alpine, Amador, Butte, Calaveras, Colusa, El Dorado, Glenn, Lassen, Modoc, Mono, Nevada, Placer, Plumas, Sacramento, San Joaquin, Shasta, Sierra, Siskiyou, Sutter, Tehama, Trinity, Yolo, and Yuba. It has 11 justices and is not divided into divisions.
The California Court of Appeal for the Fourth District is unique in that it is divided into three geographical divisions that are administratively separate, which even have different case number systems, and yet remain referred to as a single district.
The Division Two courthouse is located in Riverside. It handles appeals from Inyo, Riverside, and San Bernardino Counties. It has seven justices. It is the only California appellate court that issues a tentative opinion before oral argument.
The California Court of Appeal for the Fifth District is located in Fresno. Its jurisdiction covers the following counties: Fresno, Kern, Kings, Madera, Mariposa, Merced, Stanislaus, Tulare, and Tuolumne. It has nine justices.
California's Board of Equalization is a public agency charged with tax administration and fee collection. For the purposes of tax administration, the Board of Equalization divides the state into four Equalization Districts, each with its own elected board member.
The first Equalization District is made up of the following counties: Alameda, Colusa, Contra Costa, Del Norte, Humboldt, Lake, Marin, Mendocino, Monterey, Napa, San Benito, San Francisco, San Luis Obispo, San Mateo, Santa Clara, Santa Cruz, Solano, Sonoma, Trinity, Yolo, and a portion of Santa Barbara.
The second Equalization District is made up of the following counties: Alpine, Amador, Butte, Calaveras, El Dorado, Fresno, Glenn, Inyo, Kern, Kings, Lassen, Madera, Mariposa, Merced, Modoc, Mono, Nevada, Placer, Plumas, Sacramento, San Joaquin, Shasta, Sierra, Siskiyou, Stanislaus, Sutter, Tehama, Tulare, Tuolumne, Ventura, Yuba, a portion of Los Angeles, a portion of San Bernardino, and a portion of Santa Barbara.
The fourth Equalization District is made up of 73 of the 88 cities in Los Angeles County: Agoura Hills, Alhambra, Arcadia, Artesia, Avalon, Baldwin Park, Bell, Bell Gardens, Bellflower, Beverly Hills, Burbank, Calabasas, Carson, Cerritos, City of Industry, Commerce, Compton, Covina, Cudahy, Culver City, Diamond Bar, Downey, El Monte, El Segundo, Gardena, Glendale, Glendora, Hawaiian Gardens, Hawthorne, Hermosa Beach, Hidden Hills, Huntington Park, Inglewood, La Cañada Flintridge, La Habra Heights, La Mirada, La Puente, Lakewood, Lawndale, Lomita, Long Beach, Los Angeles, Lynwood, Malibu, Manhattan Beach, Maywood, Monrovia, Montebello, Monterey Park, Norwalk, Paramount, Pasadena, Pico Rivera, Redondo Beach, Rosemead, San Fernando, San Gabriel, San Marino, Santa Fe Springs, Santa Monica, Sierra Madre, Signal Hill, South El Monte, South Gate, South Pasadena, Temple City, Torrance, Vernon, Walnut, West Covina, West Hollywood, Westlake Village, and Whittier.