Lowest measured density of restaurants in Illinois

Coverage. Only the Illinois counties BizGapMap covers, not the whole state. A missing state page means no ZIP there cleared the test — we do not publish an empty list.

Lowest measured density is not evidence of opportunity. A low published count can mean weak demand, no suitable space, commuters spending elsewhere, or businesses with no paid employees that ZBP does not count. Each line is a question to check locally.

False positives. The test is one-sided at 5% with no correction for looking at many ZIPs. Of 280 comparable ZIPs here, about 14 could clear the bar by chance. Small ZIPs rarely reach significance, so “not on this list” does not mean “no gap”.

Who can be listed. ZIPs in the covered counties whose county has at least 15 ZIPs in our data, with at least 10,000 residents, and at least 5 published businesses in this industry. Census hides counts of 0–2; derived remainders are excluded.

Statistically low. P(X ≤ n | expected) < 0.05, where expected is the U.S. establishments-per-person-present rate times this ZIP’s demand (residents + 0.5 × jobs located here). Same definition as the index, so the percentage and the test cannot disagree. Full test →

ZIP type is jobs per resident, not zoning. A residential ZIP can look low because residents shop near work.

What does “lowest measured density” mean for restaurants? A ZIP is listed only when Census published at least 5 restaurants with paid employees, the ZIP has at least 10,000 residents, and a one-sided Poisson test finds the count statistically below the U.S. rate (p < 0.05). Index 100% is the national density per person present.

Is a low-density ZIP a place to open this kind of business? No. A low published count of restaurants can mean weak demand, no suitable space, residents shopping near work, or businesses with no paid employees that Census ZBP does not count. Each line is a question to check locally, not a recommendation.

Why is a state missing from this list? A state page exists only when at least one ZIP in the counties we cover clears the same test as the radius search. We do not publish an empty list. Coverage is those counties, not the whole state.