County · code 06081
San Mateo CountyCalifornia
San Mateo County is a county in California with its seat in Redwood City. It was created on July 1, 1856, from parts of San Francisco and Santa Cruz counties.
- Founded1856
- County seatRedwood City
- Named forMatthew the Apostle
- Land area449 sq mi + 292 sq mi water
- Population764,442 2020 Census
- Parcels mapped235,477 checked 16 October 2026
Where it is
San Mateo on the map of California
California has 58 counties and county equivalents, each with its own records office. Shapes with a page are links.
History
Formed in 1856 from San Francisco County and Santa Cruz County
An old deed may name a county that no longer exists, or a boundary that has since moved.
San Mateo County was created from San Francisco County and Santa Cruz County in 1856, with the southern boundary with Santa Cruz initially in dispute. The county gained additional territory from Santa Cruz County in 1868 and lost a small area to Santa Clara County in 1963.
- 1856San Mateo County created San Mateo created from San Francisco; southern boundary with Santa Cruz was in dispute. Act passed 19 April 1856; took effect 1 July 1856. · Calif. Stats. 1856, 7th sess., ch. 125/pp. 145-146, 176-178
- 1857Boundary clarified Boundary between San Francisco and San Mateo adjusted to run on public land survey line (no change). San Mateo boundaries clarified, ending dispute with Santa Cruz; gave San Mateo control over area disputed with Santa Cruz. · Calif. Stats. 1857, 8th sess., chs. 190, 192/pp. 209-210, 222-223; Stanger, 88
- 1868Gained territory San Mateo gained from Santa Cruz. · Calif. Stats. 1867, 17th sess., ch. 195/p. 174
- 1878Changed Boundary between San Mateo and Alameda in San Francisco Bay was adjusted. · Calif. Stats. 1877, 22d sess., Acts Amendatory of the Political Code, ch. 197/p. 71
- 1901Boundary clarified San Mateo boundaries clarified (no change).no change· Calif. Stats. 1901, 34th sess., ch. 128/p. 291
- 1963
- 1968Boundary clarified San Mateo boundaries clarified (no change).no change· Calif. Stats. 1968, reg. sess., ch. 537, sec. 1/pp. 1189-1191
Land and parcels
What the maps cover in San Mateo
Who publishes each layer, how good it is, and when we last checked.
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Parcels Good enough
Lot lines and tax-map numbers for 235,477 parcels from San Mateo County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
checked 16 October 2026 -
Address points Missing
No public address points layer found for San Mateo County yet.
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Buildings Reference
Roof outlines traced from aerial imagery from FEMA Response Geospatial Office with Oak Ridge National Laboratory (ORNL). Good for seeing what is on a lot; not accurate enough to set a fence from.
checked 18 October 2026
- Official
- from the office that keeps the record
- Good enough
- a reliable statewide or national copy
- Fallback
- a guide only; check the official record
- Missing
- nothing public found yet
People and land
San Mateo by the Census
Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.
Rules and offices
San Mateo County's official site
We have found the county's site but not its offices yet; start there.
County government
- County government
The official website of San Mateo County.
See your own lot on these maps
Open San Mateo County on Parcel Chart's free map and click your parcel. Save it with a free account; the full record of your place (site map, projects, documents) is Pro, in early access.
Questions
Common questions about San Mateo County
- When was San Mateo County founded?
- San Mateo County was founded in 1856, formed from San Francisco County and Santa Cruz County, and named after Matthew the Apostle.
- What is the county seat of San Mateo County?
- The county seat of San Mateo County is Redwood City.
- Is there an online parcel map for San Mateo County?
- Yes. San Mateo County publishes a parcel map of 235,477 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has San Mateo County's boundary or name changed?
- San Mateo County was created in 1856 from San Francisco County and Santa Cruz County. Since then the Atlas of Historical County Boundaries records 3 later changes, most of them small boundary adjustments, chiefly involving Alameda County, Santa Clara County and Santa Cruz County.
- Is my lot in a flood zone?
- We do not have flood maps for San Mateo County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby