Polco gives each area an index from the public data behind it, adjusted for the community's socioeconomic profile. Higher is stronger by Polco's measure. Where this page has the numbers behind an area, pick it to see them.

Natural environment63
Inclusivity and engagement49
Parks and recreation47
Utilities38

Source: Polco GPAL, using data from the original source shown for each indicator. The area indexes are for 2025.

Data index

What each number actually means.

Pick a number to see how Marin County compares with other communities, what Polco's model expected and what to keep in mind.

Where Marin County ranks on population

257,969 in 2024

Compared with communities nationallyHigher · 91st percentile

Compared with communities in CaliforniaSimilar · 56th percentile

Compared with communities of similar population sizeSimilar · 72nd percentile

Each dot is Marin County's percentile within that group, from Polco. Polco treats this measure as neither good nor bad, so further right only means higher.

Source: Polco GPAL, using data from U.S. Census Bureau American Community Survey. Polco’s name for this measure: “Total population”.

What it measures

2024 · Census ACS

How many people live in Marin County. The number comes from the Census Bureau's American Community Survey, and college students who live there count as residents.

What Polco's model shows

Model estimate

Polco's GPAL model projects 259,224 for 2025.

Who it affects

More residents means more demand on housing, schools, roads and local services. Population also shapes how much state and federal money Marin County receives.

Keep in mind

Survey figures are estimates with a margin of error. Small changes from one year to the next may not be meaningful.

About this data

These figures come from Polco's GPAL data, which brings together public data on U.S. cities and counties from sources like the Census Bureau, the CDC, the Bureau of Labor Statistics and the FBI. Each number is for the year shown with it, and most public data runs one to two years behind. Dollar figures are not adjusted for inflation.

The comparisons are Polco's. Each one names the group of communities Marin County is compared with, and the percentile is Marin County's place within that group. Polco's model figures are estimates, not measurements.

Polco has 329 measures for Marin County. This page shows the 69 whose units and values could be checked. Polco data release of Oct 26, 2026.

Explore Marin County on Polco →

Which of these matters most to you?

Tell us, and see how your neighbors answered. Notes and tips go to people covering Marin County.