Contra Costa County, California: New American county. In 2024, voted D+38%. Republican peak: R+48 in 1924.
Key facts
- 2024 presidential margin
- D+38MIT Election Lab
- Political typology
- New AmericanAkashic typology
- Population
- 1,165,0122024 5-year
- Median household income
- $127,2292024 5-year
- White (non-Hispanic)
- 41.1%2024 5-year
- Black
- 8.3%2024 5-year
- Hispanic / Latino
- 27.6%2024 5-year
- Peak Democratic margin
- D+46 in 1936MIT Election Lab
- Peak Republican margin
- R+48 in 1924MIT Election Lab
- Most similar
- Montgomery County, MD · similarity 1.00
2024 results by precinct
2024 precinct map of Contra Costa CountyPrecinct-level 2024 presidential results for Contra Costa County, with each precinct boundary colored by Democratic-vs-Republican margin.
—
Margin—
Turnout—
Harris +50Trump +50
Real precinct boundaries. Hover for vote totals.
presidential history
Presidential margin, 1876–2024
Democratic minus Republican, by election
| Year | Margin (D minus R) |
|---|---|
| 1876 | −17.2% |
| 1880 | −12.6% |
| 1884 | −14.3% |
| 1888 | −12.4% |
| 1892 | −9.5% |
| 1896 | −13.9% |
| 1900 | −16.2% |
| 1904 | −34.8% |
| 1908 | −31.6% |
| 1912 | +39.4% |
| 1916 | +2.8% |
| 1920 | −39.2% |
| 1924 | −48.0% |
| 1928 | −22.0% |
| 1932 | +21.6% |
| 1936 | +45.6% |
| 1940 | +24.5% |
| 1944 | +28.1% |
| 1948 | +14.6% |
| 1952 | +1.2% |
| 1956 | −2.2% |
| 1960 | +6.0% |
| 1964 | +27.0% |
| 1968 | +1.9% |
| 1972 | −10.6% |
| 1976 | −1.1% |
| 1980 | −12.8% |
| 1984 | −9.9% |
| 1988 | +3.2% |
| 1992 | +21.4% |
| 1996 | +20.6% |
| 2000 | +21.7% |
| 2004 | +25.8% |
| 2008 | +37.6% |
| 2012 | +35.1% |
| 2016 | +43.0% |
| 2020 | +45.3% |
| 2024 | +37.9% |
DemocraticRepublican
38 presidential elections
| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| D | 356,008 | 155,308 | 528,904 | ||
| D | 416,386 | 152,877 | 581,316 | ||
| D | 319,287 | 115,956 | 473,014 | ||
| D | 290,824 | 136,517 | 439,145 | ||
| D | 306,983 | 136,436 | 453,244 | ||
| D | 257,254 | 150,608 | 413,028 | ||
| D | 224,338 | 141,373 | 381,478 | ||
| D | 196,512 | 123,954 | 352,602 | ||
| D | 194,960 | 112,965 | 382,823 | ||
| D | 169,411 | 158,652 | 331,511 | ||
| R | 140,994 | 172,331 | 316,318 | ||
| R | 107,398 | 144,112 | 287,545 | ||
| R | 123,742 | 126,598 | 256,534 | ||
| R | 111,718 | 139,044 | 256,884 | ||
| D | 101,668 | 97,486 | 218,917 | ||
| D | 113,071 | 65,011 | 178,245 | ||
| D | 93,622 | 82,922 | 177,123 | ||
| R | 71,733 | 74,971 | 147,051 | ||
| D | 69,060 | 67,453 | 137,281 | ||
| D | 50,277 | 36,958 | 91,376 | ||
| D | 47,831 | 26,816 | 74,785 | ||
| D | 30,900 | 18,627 | 50,040 | ||
| D | 26,007 | 9,604 | 35,975 | ||
| D | 17,218 | 10,907 | 29,214 | ||
| R | 8,573 | 13,495 | 22,349 | ||
| R | 1,114 | 9,061 | 16,573 | ||
| R | 3,483 | 9,041 | 14,182 | ||
| D | 6,092 | 5,731 | 13,011 | ||
| O | 3,290 | 0 | 8,350 | ||
| R | 1,599 | 3,336 | 5,504 | ||
| R | 1,257 | 2,833 | 4,529 | ||
| R | 1,549 | 2,165 | 3,797 | ||
| R | 1,381 | 1,834 | 3,269 | ||
| R | 1,332 | 1,631 | 3,149 | ||
| R | 1,177 | 1,518 | 2,758 | ||
| R | 1,114 | 1,496 | 2,678 | ||
| R | 1,010 | 1,302 | 2,312 | ||
| R | 837 | 1,184 | 2,021 |
Demographics
2024 ACS
Race, ethnicity, and ancestry
Click any group to see the ancestries typically reported within it.
German
8.0%
English
8.0%
Irish
7.3%
Italian
4.7%
American
2.2%
French
1.5%
Scottish
1.5%
African American
6.6%
Multiple ancestry combinations reported; no single grouping above 1%.
American Indian, Alaska Native, Native Hawaiian, and Pacific Islander combined.
Source · American Community Survey 5-year estimates, 2024 release. Hispanic/Latino is an ethnicity that overlaps the race categories, so these shares can total more than 100%. Ancestry is a self-reported, multiple-response item; ancestry percentages do not sum to the parent race percentage.
2024 ACS
Age distribution by sex
Median age: 40.5 in this county, 39.1 nationally
Male
Age
Female
85+
75–84
65–74
55–64
45–54
35–44
25–34
18–24
5–17
<5
Source · American Community Survey 5-year estimates, 2024 release.
2024 ACS
Median household income
Inflation-adjusted dollars
$127,229
Contra Costa County ranks in the top 0.5% of US counties.
Contra Costa County$127,229
California$99,122
United States$80,734
Contra Costa County ranks in the top 0.5% of US counties by median household income.
Source · American Community Survey 5-year estimates, 2024 release.
2024 ACS
Poverty rate
All persons below federal poverty line
8.4%
Child poverty is below the national average.
Children under 1810.0%
Working age (18–64)7.8%
Seniors (65+)8.4%
Source · American Community Survey 5-year estimates, 2024 release.
2024 ACS
Language at home
Population aged 5 and older
62.5%
speak English only
Spanish19.1%
Asian & Pacific Islander10.5%
Other Indo-European6.6%
Other languages1.4%
Source · ACS 5-year estimates, 2024.
2020 religion census
Religious adherents
Adherents per capita by tradition
Source · 2020 US Religion Census. Remaining 58.5% of residents not counted as adherents by any reporting body.
Once a bellwether of white working-class suburban politics, Contra Costa has shifted decisively leftward over three decades as the population diversified and Bay Area commuter culture extended eastward into its inland cities.
Contra Costa County has leaned Democratic in recent presidential elections, reaching a Democratic margin of forty-six points in 1936. Between 2020 and 2024 it moved seven points toward the Republican candidate — part of the sharpest rightward shift recorded among any group of places in the country.
Its demographics describe the shift: a 41% non-Hispanic-white share, a median household income of $127,229, and a population of 1,165,012. The county's voting pattern over the last decade is most similar to that of Montgomery County and Santa Clara County.
Most similar counties
Compare two places, side by side
Twelve curated comparisons line up election history, demographics, and the divergence story for two places at a glance. Browse all comparisons →
Cite this page
All citations released under CC BY 4.0. Attribution: Akashic Intelligence.
Contra Costa County, California. Akashic. https://akashic.app/county/06013/. Accessed May 20, 2026. License: CC BY 4.0.
License: CC BY 4.0
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Frequently asked questions
How did Contra Costa County, California vote in 2024?
In 2024, Contra Costa County, California voted Democratic by 37.9 points (D+38), carried by the Democratic candidate. Out of 528,904 votes cast, 356,008 went Democratic and 155,308 went Republican.
What is Contra Costa County, California's political typology?
Akashic places Contra Costa County, California in the "New American" typology — Communities where a large share of households speak a language other than English — multilingual, Democratic-leaning overall, yet the hardest-swinging bloc toward the Republican Party in 2024. The typology is a data-driven cluster built from vote share, vote swing, race and ethnicity, income, language spoken at home, religion, and ancestry. Across 38 elections in the dataset, the county has voted Democratic 20 times, Republican 17 times, and other 1 times.
When did Contra Costa County, California last vote Republican?
The most recent presidential election in which Contra Costa County, California voted Republican was 1984.
How many people live in Contra Costa County, California?
Contra Costa County, California has a population of 1,165,012 according to the 2024 American Community Survey 5-year estimates from the US Census Bureau.
What is the median household income in Contra Costa County, California?
Median household income in Contra Costa County, California is $127,229 — above the national median of $80,734. The California state median is $99,122.
What is the political history of Contra Costa County, California?
Akashic tracks 38 presidential elections in Contra Costa County, California from 1876 to 2024. Of those, 20 went Democratic and 17 went Republican. The county's typology — "New American" — captures where that record, its demographics, and its recent swing place it among American communities.