by Kristen Carney
Updated: February 9, 2026
The richest county in California is Marin County with an average household income of $232,566 as of 2024 and 257,969 people as of 2024 according to the most current Census data available (citation).
| Rank | County | Population | Average Income | Median Income |
|---|---|---|---|---|
| 1 | Marin County | 257,969 | $232,566 | $149,091 |
| 2 | San Mateo County | 742,340 | $231,822 | $158,855 |
| 3 | Santa Clara County | 1,902,047 | $227,007 | $164,281 |
| 4 | San Francisco County | 830,235 | $206,854 | $140,970 |
| 5 | Alameda County | 1,649,473 | $177,144 | $129,367 |
| 6 | Contra Costa County | 1,165,012 | $174,872 | $127,229 |
| 7 | Napa County | 134,869 | $161,672 | $111,471 |
| 8 | Orange County | 3,165,820 | $156,759 | $116,289 |
| 9 | Santa Cruz County | 264,926 | $156,439 | $111,093 |
| 10 | El Dorado County | 192,662 | $150,262 | $108,845 |
| 11 | Placer County | 419,156 | $150,239 | $115,998 |
| 12 | Ventura County | 837,469 | $144,867 | $109,797 |
| 13 | San Benito County | 67,290 | $143,684 | $114,394 |
| 14 | Alpine County | 1,616 | $143,386 | $105,521 |
| 15 | Sonoma County | 485,040 | $142,354 | $104,674 |
| 16 | San Diego County | 3,288,774 | $141,250 | $106,268 |
| 17 | Santa Barbara County | 443,701 | $140,893 | $98,161 |
| 18 | San Luis Obispo County | 281,555 | $131,990 | $97,446 |
| 19 | Monterey County | 437,613 | $131,486 | $97,230 |
| 20 | Los Angeles County | 9,808,667 | $128,770 | $90,112 |
We usually suggest using median income data – either instead of or in addition to – average income data as a true indicator of wealth. If you haven’t thought about median versus average since your last standardized test, you aren’t alone. Here’s what they are:

Now let’s say you had the following simplified set of income data.
Household 1: $30,000
Household 2: $50,000
Household 3: $1,000,000
The average income for this set is $360,000. The outlier data point ($1,000,000) skews the average WAY up. Conversely, the average income would be skewed WAY down if someone had an income of $500. The median income for the same data set is $50,000. Outlier data doesn’t skew the median.
So most business owners should use the median income as a true indicator of wealth, because it provides a more accurate representation of a typical income, especially in areas with significant income disparity.
If your target market is high-income households, the average income may be more relevant. This is because the average income can highlight the presence of a higher concentration of wealthy individuals, which is beneficial for luxury goods and services marketing. We’re using average income on this page because using the Census’s highest reported median value of $250,001 could result in multiple ties for the richest geography.
The Census' American Community Survey uses $250,000+ as a jam value for median income estimates to protect privacy, ensure data consistency, and simplify reporting. A "jam value" in survey data refers to a placeholder or default value used when actual data points are unavailable, incomplete, or exceed certain thresholds. We represent this jam value as $250,001 to make it easy for you to sort.
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United States Census Bureau. Annual Estimates of the Resident Population: April 1, 2020 to July 1, 2024. U.S. Census Bureau, Population Division. Web. May 2025. http://www.census.gov/.
United States Census Bureau. B01001 SEX BY AGE, 2024 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. 29 January 2026. http://www.census.gov/.
United States Census Bureau. B19013 Median Household Income, 2024 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. 29 January 2026. http://www.census.gov/.
United States Census Bureau. “DP03 SELECTED ECONOMIC CHARACTERISTICS.” 2024 American Community Survey 5-Year Estimates. U.S. Census Bureau, American Community Survey Office. Web. 29 January 2026. http://www.census.gov/.
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