San Mateo County, CA
Migration of people and income, 2022–2023 filing years
At a glance (2023)
Cost of living is the metro-area price level for San Francisco-Oakland-Fremont, CA.
The cost of living runs about 18% above the national average. The median home is valued at $1,494,500 (nominal). Home prices have risen about 14% over the five years to 2023. Median rent is about $2,893 a month. Unemployment averaged 3.1% in 2023 (national 3.6%). Median household income is $156,000. These figures describe all residents, not just tax filers, come from separate sources than the migration data on this page, and do not indicate why anyone moved.
Between the 2022 and 2023 filing years, San Mateo County, CA saw a net loss of 2,970 tax-filing households and a net loss of 6,762 individuals. Against a population of about 726,353, that is a net outflow of about 9.3 per 1,000 residents. On net, the area lost $965.1M in associated adjusted gross income (AGI, nominal dollars). The largest inflow, about 4,514 households, came from San Francisco County; the largest outflow, about 3,874 households, went to Santa Clara County. In the prior (2022) filing year, the area saw a net loss of 11,615 individuals. These figures cover federal income tax filers only and do not indicate why people moved.
-9.3 net people per 1,000 residents (population 726,353)
Income (AGI) in and out
San Mateo County within California
San Mateo County is outlined, with arrows tracing its largest moves to and from other California counties. Hover any county for its figures; click to open it.
Where movers came from
- 1San Francisco County, CA4,514$798.9M
- 2Santa Clara County, CA3,879$975.6M
- 3Alameda County, CA2,026$301.6M
- 4Los Angeles County, CA977$139.4M
- 5Contra Costa County, CA839$101M
- 6San Diego County, CA439$50.7M
- 7Sacramento County, CA352$28.5M
- 8King County, WA329$77M
- 9Orange County, CA325$42.3M
- 10San Joaquin County, CA245$17.1M
Where movers went
- 1Santa Clara County, CA3,874$1B
- 2San Francisco County, CA3,710$609.5M
- 3Alameda County, CA2,498$361.5M
- 4Contra Costa County, CA1,313$206.4M
- 5Los Angeles County, CA900$128.3M
- 6Sacramento County, CA635$65.9M
- 7San Diego County, CA600$133.9M
- 8San Joaquin County, CA416$37.2M
- 9King County, WA397$76.9M
- 10Solano County, CA381$36.1M
Churn by county · both directions at once
The biggest two-way exchanges of filing households, 2022–2023. Moved in and moved out are gross one-way counts; net is the difference. Click a column to sort.
| San Francisco County, CA | 4,514 | 3,710 | +804 | +$189.4M |
| Santa Clara County, CA | 3,879 | 3,874 | +5 | -$34.9M |
| Alameda County, CA | 2,026 | 2,498 | -472 | -$59.9M |
| Contra Costa County, CA | 839 | 1,313 | -474 | -$105.4M |
| Los Angeles County, CA | 977 | 900 | +77 | +$11.2M |
| San Diego County, CA | 439 | 600 | -161 | -$83.2M |
| Sacramento County, CA | 352 | 635 | -283 | -$37.4M |
| King County, WA | 329 | 397 | -68 | +$158K |
| Orange County, CA | 325 | 349 | -24 | -$12.9M |
| San Joaquin County, CA | 245 | 416 | -171 | -$20.2M |
| Solano County, CA | 206 | 381 | -175 | -$16.5M |
| New York County, NY | 202 | 347 | -145 | -$1.5M |
Counts are filing households (IRS returns), matching the lists above; income is nominal AGI. A dash means the IRS published only one direction of that exchange (small flows are suppressed), so no net is computed.
Net migration by year
| Year | Net AGI | Net people |
|---|---|---|
| 2012 | +$286.2M | +670 |
| 2013 | +$280.6M | -1,211 |
| 2014 | -$30.7M | -1,996 |
| 2015 | +$159M | -2,129 |
| 2016 | -$82.4M | -7,099 |
| 2017 | -$613.8M | -10,671 |
| 2018 | -$476.7M | -8,218 |
| 2019 | +$666.7M | -8,836 |
| 2020 | -$1.7B | -16,343 |
| 2021 | -$3.2B | -21,085 |
| 2022 | -$2.6B | -11,615 |
| 2023 | -$965.1M | -6,762 |
How big is this move, relative to the county?
In the 2022–2023 filing year, about 6,762 more people left San Mateo County, CA than moved in (counting tax filers and their dependents) — a net loss of about $965.1M in income (nominal) — in a county of 733,949 people.
The rate lets you compare San Mateo County, CA with a countyof any size: it’s the net flow divided by population. The IRS counts tax filers; population counts all residents, so read the rate as a scale indicator, not a literal share of people.
Components of population change · 2023 (Census)
Where the county’s overall change came from. Census counts all residents; the IRS migration above is one slice of the domestic-migration component.
Source: U.S. Census Bureau, Population Estimates Program. Figures are people, not tax filers.
What a dollar is worth here
Prices around San Mateo County, CA run about 18% above the national average. In plain terms: $100 spent here buys about what $85 buys in the average American community. The figures below apply that to income, each compared to the U.S. average of $70,002 per person.
Cost of living shown for the San Francisco-Oakland-Fremont, CA metro area (BEA publishes price parities by metro, not by county).
Where the cost comes from · price parity by category
Index where 100 = U.S. average for that category. Housing is usually what separates one place from another.
Housing is measured from rents (including an estimated rental value for owner-occupied homes), so a run-up in purchase prices shows here only as it reaches rents. Source: U.S. Bureau of Economic Analysis. Covers all residents, a separate universe from the IRS filer income above. How the data works.
The people of San Mateo County, CA
American Community Survey, 2019–2023 (a 5-year average of all residents, not just tax filers).
White, Black, and Asian counts are people who are not Hispanic or Latino; Hispanic or Latino can be of any race. Shares are rounded and may not total 100.
Source: U.S. Census Bureau, American Community Survey 5-year estimates. Covers all residents, a separate universe from the IRS filer data. A 5-year estimate is an average over 2019–2023; compare years at least five apart, since consecutive windows overlap. How the data works.
Housing · what it costs to live here (ACS 2019–2023)
A repeat-sales index (how much the same homes changed in price), so it tracks the market over time rather than the current level. Source: Federal Housing Finance Agency, annual all-transactions HPI; the county series is FHFA’s developmental index.
Units authorized by residential building permits (new supply), summed from counties for the state and U.S. Permits are authorizations, not completions. Source: U.S. Census Bureau, Building Permits Survey.
Home value is what owners estimate their homes are worth, not recent sale prices. Source: U.S. Census Bureau, American Community Survey 5-year estimates (2019–2023), nominal dollars. How the data works.
Jobs and natural hazards
Sources: U.S. Bureau of Labor Statistics (LAUS) and FEMA. A disaster declaration marks federal assistance eligibility, not damage severity, and says nothing about why anyone moved. How the data works.
Source: U.S. Bureau of Labor Statistics (LAUS). Monthly unemployment for this county, not seasonally adjusted. Updated every month, so it moves faster than the annual average above. How the data works.
Elections
National maps →How San Mateo County, CA has voted. Certified returns, popular vote only. This is a separate dataset from the migration figures on this page.
| Year | Democratic | Republican | Other | Margin | Total |
|---|---|---|---|---|---|
| 2024 | 242,957 | 76,616 | 10,937 | D +50.3 | 330,510 |
| 2020 | 291,496 | 75,584 | 7,171 | D +57.7 | 374,251 |
| 2016 | 237,882 | 57,929 | 18,573 | D +57.2 | 314,384 |
| 2012 | 206,085 | 72,756 | 6,879 | D +46.7 | 285,720 |
| 2008 | 222,826 | 75,057 | 5,409 | D +48.7 | 303,292 |
| 2004 | 197,922 | 83,315 | 2,840 | D +40.3 | 284,077 |
| 2000 | 166,757 | 80,296 | 12,346 | D +33.3 | 259,399 |
Source: MIT Election Data and Science Lab county returns (CC0). Margins are the popular-vote gap as a share of all votes cast.
Get the next update for San Mateo County, CA
The IRS releases new migration data once a year. Drop your email and we will send the refreshed numbers when they land. No spam, unsubscribe anytime.