Blog · October 14, 2026 · California
East Palo Alto Plat Map: finding the recorded plat
Lots in East Palo Alto trace back to recorded plats filed with the county.
Main page: San Mateo County, CA GIS & Parcel Viewer (official map link, county facts and neighboring maps).
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Trying to understand lot lines near Redwood City? The East Palo Alto plat map is the document to find, since it shows lots, streets and easements as approved. In this East Palo Alto guide: where plats are filed, how a plat differs from a parcel map, and what to look for on the sheet.
The East Palo Alto plat map: start here
For a lot in East Palo Alto, the deed or parcel record often names the subdivision and plat reference; bring that to the recorder's office or its online index.
The viewer San Mateo County publishes
Go first to the San Mateo County parcel viewer; it maps every tax parcel from Portola Valley to San Carlos. If you only know roughly where the land is, pan along the nearest road and click the parcel itself, and that holds around Portola Valley too. With a lot near Atherton, the parcel card typically gives the owner of record, assessed acreage, the parcel number and often a sale date.
Which office to call
Anything recorded against property around San Carlos sit in the index kept by the County Recorder, often with an online index. Building or septic questions for a lot near Portola Valley are for the local planning and health departments, and the answer depends on jurisdiction.
Field tips
The parcel map usually runs in a mobile browser, which helps when you're standing on land near Portola Valley, so load it before you lose signal. A printout of the tract near Menlo Park is a good backup.
East Palo Alto, CA: the basics
East Palo Alto is part of San Mateo County, California, which means parcel data comes from the county. For a home near Woodside, the municipality handles matters such as zoning, permits and utilities inside its limits, and the county still keeps the parcel and deed records. Acreage past the town limits near Woodside usually answers to county rules rather than the town's.
A word on accuracy
Tax maps are drawn for assessment, not measured on the ground, so the edge of a yard near Redwood City may sit several feet off the line on screen. For a home near Redwood City, owner names and values update on a schedule, so a deed recorded last month might lag behind.
Plat map vs. parcel map
Where lines don't match in East Palo Alto, trust the recorded documents over the GIS layer.
Amended plats
An amended plat may change lots around Portola Valley, search the index for replats of the same subdivision; street vacations show up in the records too.
A quick look at the area
Redwood City is the county seat, which is where the courthouse records live. You'll also find Menlo Park, Atherton, and Woodside, where town lots give way to larger tracts. Roughly 726,353 people call San Mateo County home (Census estimate, 2023) spread over some 449 square miles. Places such as Don Edwards San Francisco Bay National Wildlife Refuge make handy reference points on the map near Atherton.
Land on the county line
San Mateo County borders 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 Portola Valley may show up in two county records, so open the neighboring map too. For a home near San Carlos, the Platbookmapper state page links every bordering county map for California.
What a plat shows
Easements on the plat near San Carlos limit where you can build or fence; check the plat notes and any covenants.
Backing up the map with records
The map is an index, not the title: deeds, plats and easements covering ground around Portola Valley sit with the County Recorder. Older tracts around Redwood City can sit on several deeds, and a title company is worth hiring on a real sale.
When there's no plat
Acreage around Redwood City outside a subdivision may have no plat at all; look for a recorded survey for land near Portola Valley.
Sections, lots and bearings
California follows the Public Land Survey System, which means a tract near Woodside is described by section, township and range. Each section is nominally a mile square, about 640 acres, and a township holds 36 of them, though real sections near Portola Valley vary in size. Write down the legal description for the tract near Portola Valley for any title or survey request.
Getting a copy
For a parcel near Woodside, some counties put plat images online, otherwise call or visit with the reference; small fees are common.
Quick answers
What do the dashed lines on a plat mean in East Palo Alto?
In most cases, building on an easement near Atherton is generally restricted, so check before you build.
Are old plats online in East Palo Alto?
For most people, older plats near Woodside may be on film or paper; call before you visit.
What is a lot and block description around Menlo Park?
For property near Redwood City, the description sends you to a specific recorded plat, so pull that plat for dimensions.
Where can I find the East Palo Alto plat map?
Recorded plats near Woodside are filed with the County Recorder; use the plat reference from the deed or parcel record.
Why don't the lines match my fence near Woodside?
No; boundary questions near Portola Valley need a licensed surveyor; a survey sets the real corners
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.