A 15-ZIP Chicago study finds sharply different inventory trends and exceptions to the idea that less supply always means faster market time.
Evidence: 15 individual Realtor.com ZIP summaries labeled August 2026.
Chicago's aggregate inventory story does not describe every local market. A review of 15 ZIP codes found 12 with lower reported active inventory than a year earlier and three with higher inventory.
The range was wide. ZIP 60636 reported inventory growth of 62.03%, while 60618 reported a decline of 25.41%. The difference between those growth readings was 87.44 percentage points.
The sample consists of the 15 ZIPs shown in Realtor.com's Chicago listing-price table. Each ZIP's individual August summary supplied the figures for this study. It is a selected sample, not a complete city census or a transaction-weighted index.
Two local readings point in different directions
In 60636, the individual summary showed 320 active listings and a median 52 days on market. Reported days on market increased 57.14% year over year.
In 60618, the summary showed 177 active listings and a median 33 days on market. Reported days on market declined 18.18%.
Those figures identify different combinations of supply and pace. They do not tell us which homes account for the differences, how property types changed, or what caused the movements. A ZIP can contain several distinct competitive sets.
Sources: Realtor.com summaries for 60636 and 60618.
Falling inventory did not always coincide with faster market time
Two ZIPs in the sample combined lower inventory with longer reported days on market. In 60609, inventory declined 7.96% while days on market increased 36.11%. In 60620, inventory declined 9.34% while days on market increased 7.25%.
Those exceptions matter because they show that the two measures do not move mechanically together. A smaller inventory pool can still contain properties that take longer to transact or leave the market.
The summaries do not establish the explanation. Changes in listing composition, asking prices and transaction volumes are possibilities that would require additional evidence.
Sources: Realtor.com summaries for 60609 and 60620.
A ZIP comparison should start the investigation
For a seller, the next step is to identify the listings buyers will actually compare with the home. Price, property type, condition, size and specific location can narrow the relevant competition considerably.
For a buyer, an increase in a ZIP's listing count does not establish that more properties meet the search criteria. Conversely, falling inventory does not mean every remaining property attracts multiple offers.
The data is useful for selecting the next comparison, not for assigning blanket labels to communities or ranking their desirability. ZIP boundaries are postal geography, not a substitute for individual property analysis.
The reporting period matters when comparing ZIP figures. Realtor.com's city comparison table and individual ZIP summaries returned different values and period labels during retrieval. Combining them would create a dataset that looks precise but mixes snapshots. This study consistently uses the August-labeled individual summaries, with the individual source rows in the study’s selected-ZIP CSV download.
Research note: Original unweighted cross-sectional analysis. Twelve ZIPs declined and three increased; ten of the twelve declining-inventory ZIPs also had shorter reported market time. Large changes in sold medians were not interpreted as appreciation because transaction counts and composition were unavailable. Attribution: Realtor.com Economic Research.