Who lives in the homes they own

How this is measured

Cook County publishes no owner-occupancy flag. Franklin County, Ohio — where our Columbus maps come from — records an explicit owner-occupied yes/no for every parcel. Cook does not, and there is no equivalent to borrow. So this map does not claim one. It compares two addresses the Assessor publishes for the same parcel: where the owner receives mail, and where the property is. If they differ, the home is counted as not owner-occupied.

The two addresses are not written the same way. The Assessor records them as separate fields, so the same place appears as “10536 S Millard” in one and “10536 S Millard Ave” in the other, or as “21 N May Street” and “21 N May St P-10”. Comparing them literally would call all of those absentee. Instead we reduce each address to its house number, the start of its street name, and its ZIP code, and compare those — which tolerates the suffixes, abbreviations and unit numbers without pretending two genuinely different addresses are the same.

How well does that work? Of the parcels this counts as owner-occupied, 98.2% have an owner address and a property address that agree on the full street name — the loose part of the match is only doing work on the remaining 1.8%, which are abbreviations like “Chicagobeach” for “Chicago Beach”. In a hand-check of 20 randomly drawn matches, all 20 were the same address written two ways.

Two things this measure is not. It is address-level, not unit-level: a condo owner who lives in unit 1303 and also owns unit 1302 counts as owner-occupied for both. And it is per parcel, not per home — a three-flat is one parcel, so an owner living in one of its units makes the whole building count. That makes this number not comparable to the Census homeownership rate, which counts households. It answers a narrower question: does whoever owns this property get their mail here?

It remains a derived signal, not an official determination. It will read a homeowner who forwards mail to a second home as absentee, and it will miss an investor who mails to one of the units they own. See methodology for the full comparison method.

The denominator is assessed residential parcels — Cook class 2xx. Parcels missing either address are left out of both the numerator and the denominator rather than being guessed at; the drawer shows what share of each area’s residential parcels that leaves covered.

Source: Cook County Assessor owner and parcel addresses, resolved to the 77 community areas. See methodology for the class-code denominator and the coverage caveat.