Blog · October 14, 2026 · California
Using the Atherton Plat Map
A recorded plat shows how land near East Palo Alto was divided into lots.
Main page: San Mateo County, CA GIS & Parcel Viewer (official map link, county facts and neighboring maps).
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When a listing near Redwood City mentions a lot number, you'll need the Atherton plat map to make sense of it. Covered here for Atherton: where plats are filed, how a plat differs from a parcel map, and what to look for on the sheet.
Tracking down the Atherton plat map
For a subdivision near Menlo Park, the deed usually cites the plat; that makes the request quick.
Where the parcel data lives
Begin with the San Mateo County parcel viewer; it maps each tax parcel around Woodside and East Palo Alto. With a lot near San Carlos, type a street address, an owner's name or a parcel number, and the viewer zooms to the match. For acreage around Woodside, the parcel card usually lists the owner of record, acreage on the tax roll, a parcel ID and often a sale date.
Next door to San Mateo County
For land near Menlo Park, San Mateo County touches Alameda County, San Francisco County, Santa Clara County, and Santa Cruz County, and each of those keeps its own parcel map. Acreage along the edge near Redwood City may show up in two county records, so open the neighboring map too. For property near East Palo Alto, our state page lists every neighboring county map for California.
The paper trail behind a parcel
For a parcel near Woodside, the map is an index, not the title: deeds, plats and easements for parcels in the county are kept by the County Recorder. Older tracts near East Palo Alto may go back through a long string of deeds, so a title company is worth hiring before a purchase.
Getting your bearings
Redwood City holds the county offices, which is where the courthouse records live. Other places on the map include Menlo Park, East Palo Alto, and Woodside, each with its own cluster of lots. For a tract near Redwood City, about 726,353 people call San Mateo County home (Census Bureau estimate, 2023) across some 449 square miles. Places such as Don Edwards San Francisco Bay National Wildlife Refuge are easy to spot when you zoom out from San Carlos.
Where Atherton fits in
Atherton is part of San Mateo County, California, which means parcel data comes from the county. Closer to Redwood City, City or town hall handles matters such as zoning, permits and utilities inside its limits, and the county still keeps the parcel and deed records. Lots just outside the town limits toward East Palo Alto usually answers to county rules instead.
Plat map vs. parcel map
If the tax map and plat differ near Menlo Park, the recorded plat and a survey control.
Land outside a subdivision
Acreage around Woodside outside a subdivision is often described by metes and bounds or survey description; the deed and any recorded survey describe it instead.
Sections, lots and bearings
California follows the Public Land Survey System, so deeds around East Palo Alto reference sections and townships. Each section is nominally a mile square, about 640 acres, and a township holds 36 of them, though real sections near Woodside vary in size. Write down the legal description for the tract near Woodside when you talk to a surveyor.
Before you lean on the lines
Acreage on the record is a tax-roll number; just a licensed surveyor establishes the real lines on land around San Carlos. For land near Woodside, owner names and values update on a schedule, so a deed recorded last month may not show yet.
Which office to call
Questions about value or the owner field for land near East Palo Alto are handled by the County Assessor, which maintains the tax roll. Questions about what you can build around Woodside need the planning or permitting office, and the answer depends on jurisdiction.
Amended plats
Lots near San Carlos can be combined or reconfigured by a replat, search the index for replats of the same subdivision; street vacations near Menlo Park show up in the records too.
Reading the plat sheet
Utility or drainage strips on a lot in Atherton limit where you can build or fence; read the notes on the sheet.
Getting a copy
For property near San Carlos, many recorder offices offer an online index, otherwise call or visit with the reference; copy fees are usually small.
Frequently asked
What is a lot and block description in Atherton?
Around Woodside, lot and block refer to a numbered lot within a block on a recorded subdivision plat, so pull that plat for dimensions.
How far back do plats go near Menlo Park?
Near Redwood City, it varies; some offices have scanned older plats and some haven't; call before you visit.
Is the Atherton plat map the same as the county GIS?
It depends, but the plat near Redwood City is recorded, while the GIS layer is an approximation; a surveyor ties it to the ground.
Who has recorded plats for land near Woodside?
In most cases, recorded plats near San Carlos are filed with the County Recorder; small copy fees are common.
Which office handles records for land near Woodside?
For land near Redwood City, assessment goes to the County Assessor and deeds to the County Recorder, while zoning questions go to planning
Open the official San Mateo County, CA parcel map See it in the Platbookmapper directory
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey, especially for fences, setbacks, or boundary disputes.