Before the 2011 redistricting, the 8th district was a Democratic stronghold. It gave John Kerry his best performance in California in 2004, backing the Democrat with 84.2% of the vote. Barack Obama continued on this trend in 2008 when he received 85.22% of the vote in the district while John McCain received 12.38%.
The 8th district from 2013-2023 was located in a politically conservative region of the state with a "Strongly Republican" Cook Partisan Voting Index of R+10. The Cook Political Report ranked it the 87th most Republican-leaning congressional district in the United States.[3]
In the 2012 election, the first after the state's adoption of top-two primaries, the 8th district was one of only two in California where two Republicans faced each other in a runoff election.[4] In 2018, it was the only such California district.[5]
As of 2023, California's 8th congressional district was significantly changed, now being located between the Sacramento and San Joaquin Valleys. It encompasses part of Contra Costa and Solano Counties.
Contra Costa County is split between this district and the 10th district. They are partitioned by Grizzly Peak Blvd, Seaview Trail, Camino Pablo, Bear Creek Rd, San Pablo Creek, Bear Creek, Brianes Reservoir, Burlington Northern Santa Fe, Highway 4, Alhambra Ave, Pacheco Blvd, Grandview Ave, Central Ave, Imhoff Dr, Bares Ave, Mount Diablo Creek, Union Pacific, Contra Costa Canal, 4WD Rd, Bailey Rd, James Donlon Blvd, Cambridge Dr, Reseda Way, S Royal links Cir, Carpinteria Dr, Barmouth Dr, Hillcrest Ave, Highway 4, and Highway 160. The 8th district takes in the north side of the cities of Antioch and Martinez, the cities of Pittsburg, Richmond, San Pablo, El Cerrito, Pinole, and Hercules.
Solano County is split between this district and the 4th 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 8th district takes in the cities of Vallejo, Fairfield, Suisun City, and Benicia.
^Center for New Media & Promotion (CNMP), US Census Bureau. "My Congressional District". www.census.gov.
^"2022 Cook Partisan Voting Index (Cook PVI) District Map". Cook PVI. Retrieved January 8, 2023.
^"Partisan Voting Index Districts of the 113th Congress: 2004 & 2008" (PDF). The Cook Political Report. Archived from the original (PDF) on March 5, 2013. Retrieved February 13, 2013.
^"California Election Results, Nov. 6th, 2012". Los Angeles Times. Retrieved February 14, 2013.
^Panzar, Javier. "Democrats look likely to get locked out of this Republican-held congressional district in California". Los Angeles Times. Retrieved July 31, 2018.
^"Results" (PDF). elections.cdn.sos.ca.gov. 1994. Retrieved August 23, 2019.
^"Results" (PDF). elections.cdn.sos.ca.gov. 1994. Retrieved August 23, 2019.
^"Results" (PDF). elections.cdn.sos.ca.gov. 1996. Retrieved August 23, 2019.
^"Statement of Vote (1998 Governor)" (PDF). September 29, 2011. Archived from the original (PDF) on September 29, 2011.
^"Statement of Vote (1998 Senator)" (PDF). September 29, 2011. Archived from the original (PDF) on September 29, 2011.
^"Statement of Vote (2000 President)" (PDF). Archived from the original (PDF) on June 11, 2007.
^"Statement of Vote (2000 Senator)" (PDF). Archived from the original (PDF) on June 11, 2007.
^"Statement of Vote (2002 Governor)" (PDF). Archived from the original (PDF) on November 11, 2010.
^"Statement of Vote (2003 Recall Question)" (PDF). Archived from the original (PDF) on May 20, 2011.
^"Statement of Vote (2003 Governor)" (PDF). Archived from the original (PDF) on May 20, 2011.
^"Statement of Vote (2004 President)" (PDF). Archived from the original (PDF) on August 1, 2010.
^"Statement of Vote (2004 Senator)" (PDF). Archived from the original (PDF) on August 10, 2011.
^"Statement of Vote (2006 Governor)" (PDF). Archived from the original (PDF) on August 10, 2011.
^"Statement of Vote (2006 Senator)" (PDF). Archived from the original (PDF) on August 10, 2011.
^"(2008 President)". Archived from the original on February 11, 2009.
^"Results" (PDF). elections.cdn.sos.ca.gov. 2014. Retrieved August 23, 2019.
^"Results" (PDF). elections.cdn.sos.ca.gov. 2016. Retrieved August 23, 2019.
^Coleman, J. Miles (January 1, 2019). "Happy New Year everyone! To celebrate, #ElectionTwitter style, we're gonna be breaking down California's statewide races - all nine of them - from last year by Congressional District. (thread)".
^"Results" (PDF). elections.cdn.sos.ca.gov. 2018. Retrieved August 23, 2019.
^"Counties by Congressional District for Recall Question" (PDF). sos.ca.gov. September 14, 2021. Retrieved May 2, 2022.
^"Counties by Congressional Districts for Governor" (PDF). sos.ca.gov. November 8, 2022. Retrieved May 4, 2023.