How to research a house in Los Angeles
The LA County Assessor parcel record, the Registrar-Recorder for deeds, Sanborn maps, the Los Angeles Public Library photo and map collections, and building permits — how to trace the history of an LA house.
By The Plot Team · May 25, 2026 · 4 min read
Los Angeles grew fast and recently — most of its housing stock dates from the 1900s onward — which actually makes the paper trail unusually complete. A Craftsman bungalow in Highland Park, a Spanish Revival in Hancock Park, a postwar house in the Valley: all are reachable. Here's the path.
Start with the parcel: the LA County Assessor
Los Angeles County is huge, and the Office of the Assessor is your anchor. Its public parcel data — keyed to the APN (Assessor's Parcel Number) — carries the situs address, the year built, the use type, and the number of units. Look up your address, get the APN and the year built, and you know which decade and which sources to chase. The Assessor's portal and the county's GIS site both let you search by address.
Trace ownership: the Registrar-Recorder/County Clerk
Deeds in LA County are recorded by the Registrar-Recorder/County Clerk (RR/CC). It maintains the official record of grant deeds, trust deeds (mortgages), and related instruments. The RR/CC offers online and in-person document search; like most California recorders it operates as a search-and-order system with per-copy fees rather than a free bulk download. Pull your chain by APN or by party name, oldest-first, to see who built, who bought, and how the house changed hands.
See the block: Sanborn maps
The Sanborn fire-insurance maps cover Los Angeles in detail and are available through the Library of Congress (and, for many sheets, the Los Angeles Public Library). They show your block footprint by footprint, color-coded by material, across editions from the late 1800s into the mid-20th century — perfect for watching a citrus grove or bean field subdivide into a street of bungalows.
The Los Angeles Public Library: photos and maps
The LAPL holds one of the best free local-history collections in the country. Its digitized photo collection (including the Security Pacific and Herald-Examiner collections) and its California Index are searchable by neighborhood and sometimes by address, and frequently surface street scenes and building photos. The Huntington Library and the USC and UCLA digital collections round out the imagery.
Building permits: an LA specialty
Los Angeles kept good building permit records, and the Department of Building and Safety offers online permit lookup by address. Original permits often name the architect, the contractor, and the original owner, and date the construction precisely — sometimes better than the Assessor's year-built. For older neighborhoods this is one of the most rewarding sources LA offers.
Find the people: census and directories
The census (public 1850–1950) names everyone in the household. LA's city directories, many digitized on the Internet Archive and held at the LAPL, fill the years between counts and let you track residents by name. Search newspapers through Chronicling America and the Los Angeles Times historical archive.
Landmark status
Check whether your house is a designated Los Angeles Historic-Cultural Monument (the city's Office of Historic Resources keeps the list and the SurveyLA citywide survey data), sits in an HPOZ (Historic Preservation Overlay Zone), or is on the National Register. SurveyLA in particular has assessed huge swaths of the city's housing and is freely searchable.
An LA specialty: tract maps and the subdivision boom
Los Angeles was built subdivision by subdivision during the great land booms of the 1880s, 1900s, and 1920s, and the tract map is the document that records it. Recorded with the County and indexed by tract number, a tract map shows when a developer carved a ranch or grove into numbered lots, and the tract's name often survives as the neighborhood's. Your parcel's legal description (visible on the Assessor's record and on your deed) names the tract and lot — follow that tract number and you'll usually pin down the exact year your street was laid out. For early-20th-century LA, the tract map plus the building permit plus the Sanborn sheet together date a house more precisely than any single source.
Read the older chain with care: into the mid-20th century many LA tracts carried racial covenants restricting who could buy, now void but still present in the recorded record — part of the city's honest history.
Let Plot assemble the LA record
Plot resolves a Los Angeles address against the County Assessor's parcel data and the broad public record automatically, then writes a cited history. For the deed chain, Plot links you to the Registrar-Recorder's official document search — the part the county keeps behind its own portal — so you can pull the instruments directly while Plot handles the rest.