Illinois Has One of the Lowest Divorce Rates in the Country. Chicago Is Its Own State's Divorce Capital.

Let's start with the number Illinois gets to feel good about.

Illinois now ranks among the states with the lowest divorce rates in the country, in the same tier as California, Massachusetts, and New York, according to 2025 family-law analysis of national divorce trends. It's part of a broader national decline — the U.S. divorce rate fell 28% between 2012 and 2022 — but Illinois has landed further down the list than most.

Zoom into the state's own county-level data and the number stops looking uniform. Cook County, home to Chicago, consistently tops Illinois's own divorce-rate rankings, according to Illinois Department of Public Health data — the same pattern this series has now found in California, Arizona, and Texas, where the state's flagship city posts a meaningfully higher rate than the rest of the state. Illinois's flattering statewide number is, in part, a statewide average smoothing over the fact that its largest, most-covered city runs hotter than everywhere else in the state.

The reason is more specific to Chicago than "it's a big city," and it has a name researchers have been documenting for decades: Chicago is the most segregated large city in America by white-Black dissimilarity, according to Brown University data reported by WBEZ, a ranking it has held for decades running. What makes Chicago's version of this genuinely distinct — not just from the rest of this series, but from most American cities — is the gap between how diverse it looks at the city level and how diverse it actually is at the neighborhood level. FiveThirtyEight's analysis of Census data found Chicago's citywide diversity index sits at 70%, the 7th-highest of the 100 most populous U.S. cities. Its neighborhood-level diversity index is just 36%, ranking 82nd. That's one of the largest citywide-to-neighborhood diversity gaps of any major American city — a place that looks, from 30,000 feet, like one of the country's most integrated cities, and looks, block by block, like one of its most divided.

This is a different mechanism than the "diversity paradox" already covered in Toronto, and it's worth being precise about the distinction. Toronto's segregation is largely cultural and social — communities that share a subway line but maintain informal, preference-driven romantic and social boundaries. Chicago's segregation is structural and historical, the direct, well-documented result of racially restrictive covenants, redlining, and contract buying that physically sorted the city's Black, white, and Latino populations into separate neighborhoods across the 20th century, a legacy researchers at WTTW and Brookings have traced in detail. The difference matters for dating specifically: Toronto's barriers are about who people choose to date across a diverse population they regularly encounter. Chicago's barriers are about how few people from other groups most Chicagoans regularly encounter in the first place, because the neighborhoods themselves were built, by policy, not to mix.

The practical effect on a city's dating market is closer to a federation of smaller markets than one citywide pool. A Chicagoan meeting people through their neighborhood, their commute, their local social circle, is drawing from a subset of the city that FiveThirtyEight's data suggests is dramatically less representative of Chicago's actual diversity than the citywide numbers imply. Two people can both accurately describe living in "one of the most diverse cities in America" while having almost no overlap in the actual population either of them regularly interacts with — a structural version of the dating-pool fragmentation problem, rather than a cultural one.

Put this next to Cook County's status as the state's own divorce leader, and Chicago's elevated rate looks less like a story about Chicagoans being unusually bad at marriage and more like the visible tail end of a much larger structural pattern: a city where forming a relationship in the first place is shaped by neighborhood boundaries drawn generations ago, boundaries that determine who's actually in a given Chicagoan's day-to-day dating pool far more than the city's celebrated, citywide diversity numbers would suggest.

None of this means Chicago singles are stuck inside their neighborhood forever — dating apps and citywide social life do let people cross these boundaries, and plenty of Chicagoans do. It means the city's dating market was never going to be explained by its statewide divorce ranking, or even by its own citywide diversity statistics. Chicago's real dating map isn't drawn at the city level. It's drawn at the neighborhood level, along lines that have very little to do with who wants to meet whom, and a great deal to do with a housing history most daters have never had a reason to learn.