Buying in San Mateo County, California

San Mateo County at a glance

San Mateo County is one of 58 counties and county-equivalents in California. Its county seat is Redwood City. County government publishes its offices and parcel tools online. Official county website. Its 2024 Census Bureau population estimate is 742,893 across 448 square miles of land — about 1,657 people per square mile. In the FBI's 2024 reported-crime file, agencies here reported 14,975 offenses — 20.16 per 1,000 residents; the breakdown is below.

Records to check before you buy in San Mateo County

• Property record card — the San Mateo County assessor / appraisal office. Pull the parcel's assessed-value history, exemption status, and last sale. This is the file your future tax bill is calculated from, and it shows whether the current owner is enjoying exemptions you will not inherit. County government sits in Redwood City; the official county website is the reliable route to the parcel search and the office directory.
• Deeds & liens — the San Mateo County recorder / land-records office. Read the deed chain, open liens, easements, and plat maps — the file a listing never mentions.
• Official flood determination. Check the exact parcel on FEMA's National Flood Hazard Layer — not the listing site's licensed model. Zone boundaries cut through streets; the house next door can be in a different zone. San Mateo County is the primary county for 30 ZIP codes in the Census Bureau's ZIP-to-county crosswalk — and zone lines ignore every one of them.
• The county's reported-crime record. In the FBI's 2024 file, agencies in San Mateo County reported 14,975 offenses — 20.16 per 1,000 residents; the largest single category was larceny-theft (10,334). The crime section below sets that beside the California county median.
• Registry check. Run the address through California Megan's Law Website (California Department of Justice) and note the counts within a mile — then check again the week you close.
• Permits & code history — the San Mateo building department. Open permits, expired permits, and code cases tell you whether the renovation in the photos was ever inspected. County permitting is run out of Redwood City.
• School assignment — the district office, not the listing. Only the district's own boundary lookup confirms which school an address is actually zoned for.

County list, land area and population: U.S. Census Bureau (population: 2024 PEP estimate). County seat and official website: Wikidata (CC0), checked 2026-11-04. Flood determinations: FEMA. Registry: California.

Reported crime in San Mateo County — FBI 2024

Reported crime in San Mateo County in 2024 was overwhelmingly property crime: agencies logged 14,975 offenses, of which 12,992 were property offenses and 1,983 violent. The total rate is 20.16 per 1,000 residents (violent 266.9, property 1748.8 per 100,000).

Inside California, the median county in the same file recorded a violent-crime rate of 458 per 100,000 and a property-crime rate of 1,315 per 100,000 (medians computed from the FBI 2024 county file across 58 counties).

The largest reported categories were larceny-theft (10,334), motor vehicle theft (1,697) and aggravated assault (1,221).

Coverage: 21 of 21 law-enforcement agencies assigned to this county reported at least one month of 2024 offense data to the FBI; 20 reported all 12 months. Counts are reported offenses only (FBI Return A / Arson master files), assigned whole to each agency's primary county; they are not adjusted for non-reporting agencies.

These are offenses reported to law enforcement — not convictions, and not a verdict on any street or address. A CurbFacts report pairs this county record with the ZIP-level picture for the specific address you are buying.

Source: FBI Crime Data Explorer, UCR Return A + Arson master files, data year 2024 (pulled 2026-11-04).

ZIP guides in San Mateo County

Registry counts and county crime records for the 22 ZIP codes whose primary county is San Mateo County.

The California rules that apply in San Mateo County

Traps researched for California buyers: Proposition 13 sale reset and supplemental tax bill; Natural Hazard Disclosure is separate from the condition disclosure.

Read the full California guide — disclosure standard, tax math, registry and flood

More California counties

All California counties · California buyer guide