Home/Cook County, IL
Illinois -- population 5,272,775

Cook County, IL Property Research

Real data from four public sources, not an internal estimate: the EPA's radon zone classification, Census housing-age records, FEMA's natural hazard risk index, and NOAA's recorded storm history for this county. Every figure below links to where it actually comes from.

Hazard Summary

Cook County, IL hazard summary: FEMA National Risk Index rated Very High; EPA radon zone 2 of 3; most frequently recorded hazard is thunderstorm wind (519 events, 2015-2024).

Radon Risk

Zone 2 -- moderate potential. EPA predicts an average indoor radon screening level between 2 and 4 pCi/L for this county.

This is a county-wide prediction from geology and soil data, not a measurement of any specific home -- EPA recommends testing every home regardless of zone. See our guide on negotiating radon mitigation after inspection.

Source: EPA Map of Radon Zones

Housing Age

Cook County has 2,270,349 housing units. About 62% were built in 1969 or earlier -- old enough that knob-and-tube wiring, lead-based paint, and galvanized supply lines are all realistic possibilities worth checking for, not just a general inspection line item.

2020 or later
7,617
2010-2019
92,794
2000-2009
174,889
1990-1999
143,888
1980-1989
168,009
1970-1979
280,324
1960-1969
285,461
1950-1959
327,665
1940-1949
155,239
1939 or earlier
634,463

Does knob-and-tube wiring have to be replaced before closing?

Source: U.S. Census Bureau, ACS 5-Year Estimates, Table B25034

Natural Hazard Risk

FEMA rates Cook County's overall natural hazard risk as Very High, relative to the rest of the country.

Cold WaveVery High
Winter WeatherVery High
TornadoVery High
Inland FloodingVery High
Heat WaveVery High
Source: FEMA National Risk Index

Recorded Storm History (2015-2024)

NOAA recorded 980 storm events in Cook County between 2015 and 2024. This is actual event history, not a risk model -- the counts below are individually logged storms, not a prediction.

Thunderstorm Wind
519
Hail
171
Flood
108
Flash Flood
67
Heavy Rain
49
Tornado
33
High Wind
22
Winter Weather
11
Source: NOAA National Centers for Environmental Information, Storm Events Database

Guides Relevant to This County's Housing Stock

Does a Standard Home Inspection Check for Asbestos?Can Cast Iron Sewer Pipes Fail a Standard Home Inspection?Can I buy a house with knob-and-tube wiring?Can You Get Homeowners Insurance with Knob and Tube Wiring?Does Knob and Tube Wiring Have to Be Replaced Before Closing?What Is a Federal Pacific Stab-Lok Panel and Why Inspectors Flag It?

Get Your Free Property Report

BeforeRegret pulls live seismic hazard data, validates the address, and builds era- and county-specific inspection priorities and seller questions into one report -- with anything not yet independently verified clearly labeled, not guessed at.

Get Your First Report Free

This page reports what these four public agencies have published for Cook County as a whole -- it is not an assessment of any specific address or property, and does not replace a licensed home inspection, radon test, or insurance review for a specific home. Data last checked August 10, 2026.