These are California’s wealthiest counties. Do you live in one?
Live in California? There’s a chance you call one of the nation’s wealthiest counties home.
California had four of the 10 richest counties in the United States in 2025 — more than any other U.S. state, according to SmartAsset.
What’s more, the state of California ranked 12th in the nation in terms of net worth, the financial advising website said.
SmartAsset created an interactive map showing the wealthiest counties across the country based on earnings, investment income and home value in 2025, the most recent data available.
Find out what counties are the wealthiest in California.
What is the wealthiest county in California?
According to SmartAsset, San Mateo County was the richest county in California in 2025 with a wealth index of 68.36 out of 100.
Part of the San Francisco Bay Area, San Mateo County offers a “mix of unbeatable weather, charming seaside views and technical resiliency, Built In San Francisco said, making it a popular location for established tech companies and startups.
About 17% of San Mateo County residents work in professional, scientific, technical or administrative jobs, according to the county’s employment data.
County residents had a median income of $156,000, according to SmartAsset.
That’s about $56,000 more than the statewide median household income of $99,122 a year, according to data from the U.S. Census Bureau.
San Mateo County residents earned an average of $146,000 in investment income.
Homes in San Mateo County had a median value of $1.5 million.
In comparison, the average California home was valued at $765,036 as of Wednesday, April 8, according to real estate website Zillow.
What are the 10 richest counties in California?
According to the SmartAsset study, the wealthiest counties in the Golden State could be found primarily in Northern California and the Central Coast.
They were:
No. 1: San Mateo County
- Median income: $156,000
- Investment income: $146,004
- Median home value: $1,543,376
No. 2: Santa Clara County
- Median income: $159, 674
- Investment income: $112,827
- Median home value: $1,501,824
No. 3: Marin County
- Median income: $142,785
- Investment income: $143,012
- Median home value: $1,438,437
No. 4: San Francisco County
- Median income: $141,446
- Investment income: $121,278
- Median home value: $1,325,267
No. 5: Alameda County
- Median income: $126,240
- Investment income: $47,498
- Median home value: $1,080,745
No. 6: Santa Cruz County
- Median income: $109,266
- Investment income: $61,372
- Median home value: $1,138,101
No. 7: Orange County
- Median income: $113,702
- Investment income: $69,515
- Median home value: $1,003,290
No. 8: Contra Costa County
- Median income: $125,727
- Investment income: $59,386
- Median home value: $812,631
No. 9: Napa County
- Median Income: $108,970
- Investment Income: $103,509
- Median Home Value: $873,494
No. 10: Santa Barbara County
- Median income: $95,977
- Investment income: $122,427
- Median home value: $885,640
What are the wealthiest counties in the US?
According to SmartAsset, these were the 10 richest counties in the United States in 2025, based on median income, investment income and home value:
- Teton County, Wyoming
- Pitkin County, Colorado
- Nantucket County, Massachusetts
- San Mateo County
- Santa Clara County
- Summit County, Utah
- Marin County
- San Francisco County
- Loudoun County, Virginia
- Falls Church City, Virginia
According to SmartAsset, California is ranked 12th in the nation in terms of net worth, having an average of $273,800.
How does Smart Asset come up with its ranking?
To determine the richest counties in California and the nation, SmartAsset said it calculated a wealth index for all U.S. counties based on median income, investment income and property, and ranked them according.
To rank the highest median net worths in the United States, SmartAsset said it looked at “the median household net worth, comprised of retirement savings, deposit accounts, home equity and other investments minus debts.”
Data came from sources including the IRS, Zillow, Census 2023 - American Community Survey.
This story was originally published April 9, 2026 at 6:00 AM.
