How to research a house in Chicago
The Cook County recorder for deeds, the city's building-footprint open data for year-built and units, Chicago's deep newspaper archives, and Sanborn fire-insurance maps — a practical guide to tracing a Chicago house.
By The Plot Team · May 26, 2026 · 3 min read
Chicago is a city that documents itself well, and a fair amount of that documentation is online and free. Whether you live in a Bridgeport workers' cottage, a Logan Square greystone, or a Hyde Park apartment, the research path is the same. Here it is.
Start with the building: Chicago's footprint data
The City of Chicago publishes its Building Footprints dataset on the city's open-data portal — and unlike many cities' geometry-only layers, it carries real attributes per building: the year built, the number of stories, the number of units, and the street address. Look up your address and you have an immediate anchor: roughly when the building went up and how big it was. As always, treat an early year-built as approximate — but it tells you which census and which maps to pull next.
For the assessment and ownership picture, the Cook County Assessor and the Cook County Clerk both publish property data and a parcel (PIN) lookup. The PIN is your key to the records that follow.
Trace ownership: the Cook County recorder
Deeds in Chicago are recorded at the county level. Recorder of Deeds functions in Cook County are now handled by the Cook County Clerk's Office, which runs an online property-records search. You can look up recorded documents — deeds, mortgages, liens — by PIN or by grantor/grantee name.
Be realistic about what's free here: like most American county recorders, it's a search portal, not a bulk feed. You can pull your own chain a document at a time, and copies of older instruments may carry a per-page fee. For deeds older than the digitized index, the Clerk's office and the Cook County land records reading room hold the bound tract books.
Find the people: census and directories
The federal census (public 1850–1950 under the 72-year rule) names everyone in the household with ages, occupations, and birthplaces — invaluable in a city built by waves of German, Irish, Polish, Italian, and later Black and Mexican migration. Search by address or surname through the National Archives, FamilySearch, or the 1950 census site.
Between censuses, the Chicago city directories — many digitized on the Internet Archive — list residents by name and occupation year by year, and help you track when a family moved in or out. The Newberry Library holds a superb genealogy and local-history collection if you need to go deeper.
Read the papers
Chicago newspapers are exceptionally well digitized. The Library of Congress's Chronicling America carries historical Chicago titles for free, and the Chicago Tribune and Chicago Public Library offer additional searchable archives. Search your street name in quotes; real-estate columns, building-permit notices, and neighborhood news regularly name specific addresses.
See the block: Sanborn maps and the Great Fire line
The Sanborn fire-insurance maps are essential in Chicago. Available through the Library of Congress, they show your block building-by-building, color-coded by construction material — brick, stone, frame — across multiple editions. They're particularly revealing here because of the 1871 Great Fire: the city's post-fire ordinances pushed masonry construction in the burned district, so a Sanborn sheet often shows exactly where the frame cottages survived at the city's edge and where brick took over. The Newberry and the Chicago History Museum hold additional historical map collections.
Landmark status
Check whether your building sits in a Chicago Landmark district (the city's Commission on Chicago Landmarks publishes designation reports) or on the National Register of Historic Places. Designation reports often contain a ready-made architectural and ownership history.
Let Plot pull the Chicago record for you
Plot resolves a Chicago address against the city's building data and the broad public record automatically — the year built, the lot, the press mentions, the archival imagery — and writes it up as one cited history. For the deed chain specifically, Plot points you straight to the Cook County Clerk's recorder search so you can pull the documents the county doesn't expose in bulk; everywhere it can, it does the gathering for you.