Territory Intel drop · Age wave
1954: the median Cook home is older than the interstate system.
Sort 1,114,319 dated Cook County residential parcels by build year and stop in the middle. You land on 1954. What follows is where that age sits, which townships carry it, and what happens when you subtract the homes that already replaced a roof.
1954Median year built, county-wideCounty assessor
53.2%Built before the 1956 interstate actCounty assessor
877,571Pre-1980 homes with no roof permit on fileAssessor + county permits
90 yrsSpread between the oldest and youngest township medianCounty assessor
01 · The median
Half this county was standing before the highways were.
The assessor's file carries a build year for 1,114,319 of its 1,114,335 residential parcels. Sixteen rows are blank. They are dropped, and every percentage on this page is a share of the 1,114,319 that are dated.
The median lands on 1954. President Eisenhower signed the Federal-Aid Highway Act, the law that started the Interstate Highway System, on June 29, 1956. The typical Cook County house was already two years old that morning.
The line survives a closer look. 592,445 homes, 53.2% of the dated stock, were finished before 1956. 942,389 of them (84.6%) predate 1980. 365,065 (32.8%) predate 1940, and 82,867 were built before the twentieth century began.
The read for contractors
A median of 1954 means the coin-flip house in this county has already outlived two or three generations of asphalt roof. Finding volume in a market like this is easy. Sequencing it is the whole job.
Share of stock by eraAssessor · n=1,114,319
02 · The shape
One decade built a fifth of the county.
Run the histogram and the county's building history stops being a smooth ramp. The 1920s put up 127,671 homes. The 1930s put up 24,443. Cook County built roughly one house in that decade for every five it had built in the one before, and the Depression gap is still legible in the roof stock ninety years later.
Then the surge. The 1950s alone account for 249,244 homes, 22.4% of everything standing. Put the whole modern era against it: everything Cook County has added since 1980 comes to 171,930 homes. That single postwar decade outbuilt the entire period from 1980 to now, combined, and it did it in dense, uniform subdivisions rather than scattered infill.
The tail end is thin. The 2010s and 2020s together contribute 22,983 parcels, about 2.1% of the county. New construction is not going to dilute this age profile on any timeline a contractor plans against.
The read for contractors
Cohorts age together. A 1950s subdivision reaching its third roof cycle does it street by street rather than house by house, which is why the county's biggest build decade is also its most concentrated replacement surface.
Homes by build decadeAssessor · n=1,114,319
03 · The spread
Ninety years separate the oldest township from the youngest.
County medians hide the thing that matters to a route. Break the same column out by township and the range runs from South Chicago at 1904 to Lemont at 1994. Every one of the 38 townships clears the 2,000-parcel floor used here, so none of that spread is a small-sample artifact.
Nineteen townships, exactly half the county's roster, carry a median build year earlier than 1956. Those nineteen hold 619,090 homes between them, 55.6% of the dated stock. The other half sits in the postwar and modern bands: Schaumburg at 1973, Hanover at 1984, Orland at 1987.
The old end is not one kind of place either. It runs from dense city townships like Jefferson (111,925 homes, median 1927) through streetcar suburbs like Oak Park (median 1916) to the north-shore stock in New Trier (median 1953). Same vintage, very different jobs, very different tickets.
The read for contractors
Pick territory by median build year and you are choosing your product mix before you knock a single door. A 1904 median means century-old framing and mixed materials; a 1973 median means uniform tract stock where one estimate template covers a whole block.
Oldest townships by median build yearAssessor · min 2,000 parcels
| Township | Median built | Homes |
|---|---|---|
| South Chicago | 1904 | 15,806 |
| West Chicago | 1906 | 65,918 |
| Lake View | 1908 | 24,697 |
| North Chicago | 1908 | 5,387 |
| Oak Park | 1916 | 11,237 |
| Cicero | 1922 | 13,691 |
| Berwyn | 1925 | 12,955 |
| Hyde Park | 1926 | 64,060 |
| Jefferson | 1927 | 111,925 |
| Evanston | 1927 | 12,991 |
| Lake | 1944 | 142,553 |
| Lemont (youngest in county) | 1994 | 8,105 |
04 · Age minus permits
The oldest stock is the least permitted.
Age on its own tells you almost nothing a competitor doesn't also know. The useful question is what share of that aged stock has no record of having replaced anything yet. Join the assessor file to the county roof-permit record and the answer is blunt.
Of the 942,389 pre-1980 homes, 64,818 carry a roof permit on file. 877,571 do not: 93.1% of the county's pre-1980 stock, with no roof permit against it in the county's permit record.
Now the part worth sitting with. Permit rates run backwards against age. Homes built in the 1900s carry a roof permit 4.4% of the time. The 1950s cohort, 7.2%. The 1970s, 10.6%. The 1980s cohort peaks at 11.9%, more than double the oldest band. The stock that has been aging longest is the stock with the least evidence of anything having been done to it.
Some of that gap is real backlog and some of it is a permit record that reaches newer municipalities more thoroughly than older ones, which is the next section. Both readings point the same direction for planning purposes: the replacement wave in this county is not approaching. It is overdue, and it is stacked in the oldest cohorts.
The read for contractors
Age alone is table stakes; age minus recent permits is a campaign. Suppressing the 64,818 pre-1980 homes that already pulled a permit costs nothing and takes a full postage line off the budget before the first drop prints.
Share with a roof permit on file, by build decadeAssessor + county permits
05 · Where the record reports
The permit file is honest about some townships and silent about others.
Two limits belong on the table before anyone builds a plan on the number above. First, the county roof-permit record is a recent window: of its 94,645 rows, only 17 carry a permit year before 2018. A pre-1980 home with no roof permit on file has no permit in a 2018-to-2026 record, which is a very different statement from never having been re-roofed.
Second, reporting is uneven by township. 82,591 permit rows match a residential parcel in the assessor file. But Calumet Township shows 0 matched roof permits across 4,651 homes, Norwood Park shows 1 across 8,203, and Proviso shows 105 across 42,151. Those are municipal reporting gaps. Roofs in Calumet age on the same clock as roofs anywhere else in the county.
So the permit cross gets a coverage floor. Keep only townships where at least 5% of all homes carry a matched roof permit, meaning the record demonstrably reaches them. That leaves 23 townships and 494,473 homes. Inside that cleaner set, 377,682 homes predate 1980 and 323,143 of them (85.6%) have no roof permit on file. The county-wide 93.1% is the ceiling; 85.6% is the number to plan against.
The league table is where it gets actionable. Palos has absorbed the most: 70.9% of its pre-1980 stock is unpermitted, the lowest gap in the county. Evanston follows at 72.9%. At the other end, Northfield sits at 95.4% and Schaumburg at 93.6%, both places where a well-reported permit file still shows almost nothing coming off the aged pile.
The read for contractors
The 24-point spread between Palos and Northfield is the whole argument for choosing territory on data. Same county, same weather, same aging clock, and a quarter of the aged cohort's worth of difference in how much of the demand has already been taken.
Pre-1980 stock with no roof permit on fileTownships with ≥5% permit coverage
| Township | Pre-1980 homes | No permit |
|---|---|---|
| Northfield | 16,006 | 95.4% |
| Schaumburg | 22,457 | 93.6% |
| Bloom | 23,350 | 91.7% |
| Wheeling | 29,345 | 89.9% |
| Maine | 32,212 | 89.8% |
| Palatine | 18,658 | 89.6% |
| Elk Grove | 17,115 | 86.8% |
| Bremen | 25,943 | 82.4% |
| Worth | 38,556 | 80.0% |
| Cicero | 13,484 | 79.5% |
| Evanston | 12,390 | 72.9% |
| Palos | 9,512 | 70.9% |
06 · Who owns it
The aged stock is owner-occupied and it is asphalt.
Two more facts finish the picture, because an aging cohort only matters if you can reach the person who decides and sell the product they actually have.
792,241 of the pre-1980 homes are owner-occupied on the assessor's file, 84.1% of that cohort. The decision-maker usually lives at the address, which keeps the sales cycle short and the mail addressable.
And the product is uniform: 844,907 pre-1980 homes carry an asphalt shingle roof, 89.7% of the pre-1980 parcels with a roof material recorded. One product, one replacement cycle, more than eight hundred thousand houses running it. Differentiation in a market that uniform comes from picking which houses to talk to, since the shingle will never supply it.
The read for contractors
Old, owner-occupied, and asphalt is the cleanest demand profile an exterior trade gets. Cook County holds 729,385 homes that are all three at once. The hard part is knowing which blocks your three nearest competitors already worked.
Pre-1980 cohort profileAssessor · n=942,389
Method & sources
Housing-age figures are computed from the Cook County Assessor's residential property-characteristics file as staged by TerritoryX: 1,114,335 parcels, of which 1,114,319 carry a usable build year. The 16 parcels with a null build year are excluded from every denominator on this page, so all age percentages are shares of 1,114,319. The median is the value at the midpoint of the sorted build-year column. Township figures use the assessor's township name. All 38 named townships clear the 2,000-parcel minimum applied here (the smallest, River Forest, holds 2,965), and the 9,478 dated parcels carrying no township name are excluded from every township table.
Permit figures come from the county roof-permit record joined to the assessor file on parcel identifier. That record contains 94,645 rows, of which 82,591 match a residential parcel in the staged file; only 17 rows carry a permit year earlier than 2018, so "no roof permit on file" means no matched roof permit in a record that effectively spans 2018 through 2026. Reporting into that record is uneven by municipality: several townships show near-zero matched permits across tens of thousands of homes. The township permit-gap table is therefore restricted to the 23 townships where at least 5% of all homes carry a matched roof permit.
The June 29, 1956 signing date for the Federal-Aid Highway Act is from the Dwight D. Eisenhower Presidential Library's Interstate Highway System document collection.
Everything on this page is aggregate. No individual home, address, parcel identifier, or owner is identified, and nothing here is a claim about any specific property's condition. The same layers, scored neighborhood by neighborhood, are what a Territory X-Ray runs on. Figures are recomputed as the county files update.
Cook County Assessor · build year, roof material, ownership
County permit records · roof permits
Eisenhower Presidential Library · 1956 highway act date
Your territory has its own age wave. And its own permit gap.
This is the county-level read. The Territory X-Ray runs the same layers on the specific towns you work: ranked neighborhoods, reason codes, and the first campaign worth your money. Start with the Territory Intelligence hub for the township briefs.
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