Marin County, California Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 26th-largest in California
The population of Marin County, California is 258,765 as of the 2023 American Community Survey, making it the 26th-largest county in California. The median household income is $142,785, the median home value is $1,390,000, and the median age is 47.3.
The population of Marin County has grown 1.4% since 2010 (252,906 → 256,400), a +0.10% annualized rate.
258,765
Population
+0.10%
Annual growth
497
People / sq mi
$142,785
Median Income
$1,390,000
Median Home Value
Marin County covers 520 sq mi of land at 497.5 people per square mile.
About Marin County, CA
In Marin County, home values do the distinguishing — a median of $1,390,000. Marin County is a county in California with a population of 258,765. It ranks #26 among counties in California by population.
Households here are among the highest-earning of all US counties: median income is $142,785, above the US median of $78,538. Hardship is rare relative to US counties: a poverty rate of just 4.0%, below the national 12.4%. Real estate commands a premium here — a median home value of $1,390,000, with typical rent around $2,584.
Degree attainment is near the top of the range for US counties: 60.5% of adults 25+ hold a bachelor’s, above the 35.0% national rate. An unusually large 27.9% of workers are remote, above the national 14.0%, and the average commute runs about 28 minutes each way.
High housing values reframe the income picture in Marin County — even solid earnings stretch less against home prices and rents at this level.
Marin County Population History (2010-2024)
The county of Marin County had a population of 252,906 in 2010 and 256,400 in 2024, a 1.4% growth over 14 years. The peak was 261,341 in 2020. Average annual growth rate: 0.10%.
256,400
Population (2024)
252,906
Population (2010)
261,341
Peak (2020)
0.10%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 252,906 |
| 2011 | 255,380 |
| 2012 | 256,087 |
| 2013 | 258,441 |
| 2014 | 260,403 |
| 2015 | 260,974 |
| 2016 | 260,722 |
| 2017 | 259,975 |
| 2018 | 260,091 |
| 2019 | 259,085 |
| 2020 | 261,341 |
| 2021 | 259,254 |
| 2022 | 257,143 |
| 2023 | 255,706 |
| 2024 | 256,400 |
Race & Ethnicity
| White | 70.4% |
| Black or African American | 2.3% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 1.9% |
| Two or More Races | 0.0% |
Age & Sex
47.3
Median Age
50.9%
Female
49.1%
Male
23.2%
Age 65+
Age Distribution
Children (under 15): 15.6% · Seniors (65+): 23.2%
Income & Poverty
| Median household income | $142,785+$46,451 vs state |
| Mean household income | $224,140 |
| Per-capita income | $90,408 |
| Poverty rate | 4.0%-4.4% vs state |
| Unemployment rate | 3.8% |
| Employment-to-population | 58.8% |
Top Industries by Employment
The largest employment sector in Marin County is finance & real estate, accounting for 21.9% of workers.
How residents commute
4.9%
Drive alone
3.5%
Carpool
53.7%
Public transit
27.9%
Work from home
28.3 min
Avg commute
Housing
$1,390,000+$694,600 vs state
Median home value
$2,584
Median rent
63.9%
Homeownership rate
111,860
Total housing units
92.3%
Occupied
7.7%
Vacant
36.1%
Renter-occupied
Social & access
96.2%
With health insurance
97.5%
With broadband internet
28.0%
Foreign-born
3.8%
Veterans (18+)
9.7%
With a disability
76.9%
Speak language other than English at home
Education
92.7%
High School+
60.5%
Bachelor's+
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Other counties in California
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Metro areas in California
County rankings
Frequently Asked Questions
Marin County, California has a population of 258,765 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 26th-largest county in California. Population density is 497 people per square mile.
The population of Marin County has grown 1.4% since 2010 (252,906 → 256,400), a +0.10% annualized rate.
The median household income in Marin County, California is $142,785, with mean (average) household income of $224,140 and per-capita income of $90,408. 4.0% of residents live below the federal poverty level.
In Marin County, the largest racial and ethnic groups are White (70.4%), Black or African American (2.3%), Hispanic or Latino (1.9%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Marin County, California is 47.3 years. Residents are 50.9% female and 49.1% male.
The median home value in Marin County is $1,390,000 and median monthly rent is $2,584. 63.9% of occupied housing units are owner-occupied. The county has 111,860 total housing units, 7.7% of which are vacant.
The largest employment sector in Marin County, California is finance, insurance, and real estate, employing 21.9% of workers. The unemployment rate is 3.8%.
Los Angeles is among the largest cities associated with Marin County, California, with a population of 3,857,897.
Marin County, CA Climate
Marin County, CA has an average annual temperature of 13.8°C (57°F) and receives about 1086 mm of precipitation per year. The warmest month is August and the coldest is January. Figures are 1970–2000 climate normals.
13.8°C
Avg Temp
1086
Precip (mm/yr)
Aug
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | 9° / 48° | 226 mm |
| February | 10° / 51° | 188 mm |
| March | 11° / 52° | 156 mm |
| April | 13° / 55° | 63 mm |
| May | 14° / 58° | 22 mm |
| June | 16° / 61° | 6 mm |
| July | 18° / 65° | 2 mm |
| August | 18° / 65° | 4 mm |
| September | 18° / 65° | 12 mm |
| October | 16° / 61° | 59 mm |
| November | 12° / 54° | 159 mm |
| December | 9° / 49° | 189 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit Marin County, CA
The most comfortable months to visit Marin County, CA are typically August, July and September, when temperatures are mildest and rainfall is relatively low. The hottest month is August (around 26°C high). The coldest is January (near 4°C low). January is usually the wettest month.
Where to stay near Marin County
Visiting or relocating to Marin County, CA? Compare hotels and short-term rentals across the county — live availability and prices.
Top-rated places to stay near Marin County
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.