America’s loneliness problem may not be a failure of social skills, but of design — suburbs, cars, and homes built for private family life, with fewer everyday reasons to meet the people next door

Most explanations of American loneliness are explanations of character. People have forgotten how to talk to strangers. They spend too long on their phones. They have grown guarded, or busy, or too comfortable to bother knocking on a door. Each of these carries some truth, and each puts the problem inside the person who is lonely.

A paper published in June in Nature Sustainability points somewhere else: at the shape of the street.

Arianna Salazar-Miranda, at the Yale School of the Environment, set out to answer a question that sounds academic but sits underneath a great deal of ordinary life. When suburbs leave residents more cut off from one another, is that because of where they sit, far from the centre of things, or because of how they are built? Her paper, Neighbourhood design and the environmental and social costs of suburbanization, tries to separate the two.

This is one study, not settled consensus, and it measures something narrower than the feeling most people have in mind when they say they are lonely. But it is careful work, and it isolates a variable that usually gets waved away as personality.

What the paper measured

Salazar-Miranda built a composite measure of what planners call garden city design: winding streets, cul-de-sacs, and the branching, hierarchical road networks that became the default template for twentieth-century American suburbs. She scored more than 60,000 neighbourhoods on how closely their street layouts and block shapes matched that template, then estimated its effect on three outcomes: greenhouse gas emissions, sedentary behaviour, and social isolation. The last two were drawn from anonymised smartphone movement data from 2019.

To push past simple correlation, she used several methods, including an instrumental-variable approach that leans on the historical timing of when this design style spread. Neighbourhoods drawn in the garden city mould came out worse on all three measures. Design alone accounted for somewhere between a quarter and two-fifths of the isolation and environmental costs usually pinned on suburbs as a category.

Two neighbourhoods the same distance from downtown can produce different amounts of isolation, depending on whether their streets connect outward or curl in on themselves.

Isolation is not the same as loneliness

The most useful thing to hold onto here is what the numbers are, and what they are not. The isolation figure comes from where phones went and how often their owners crossed paths with others. Nobody in the dataset was asked whether they felt alone. Movement is a reasonable stand-in for the chance to meet people, but it says nothing about the inner state.

That gap matters, because the two ideas are constantly folded together. The 2023 US Surgeon General’s advisory on loneliness kept them apart on purpose: isolation is the objective thinness of a person’s contacts, while loneliness is the felt gap between the connection someone has and the connection they want. Around half of American adults, the advisory reported, called themselves lonely even before the pandemic. Someone can be isolated without feeling lonely, or lonely in a full room.

So the paper does not show that cul-de-sacs make anyone unhappy. It shows that certain layouts cut down the number of unplanned, everyday encounters a person has. Those encounters are the raw material of acquaintance, and it is acquaintance, more than deep friendship, that tends to be missing when people say they do not know anyone on their street.

The oldest finding in this field

Researchers who study how friendships form have known the outline of this for a long time. In 1950, Leon Festinger, Stanley Schachter and Kurt Back published a study of a student housing complex, Social Pressures in Informal Groups. Who befriended whom, they found, was predicted less by temperament than by the building. People became friends with those whose front doors they passed, whose stairwells they shared, whose letterboxes sat beside their own. They named it functional distance: not how many metres separated two homes, but how often the design of the place threw their occupants together.

That was one building, but the pattern has held up across decades of study. A 2019 review in the Annual Review of Sociology by Mario Small and Laura Adler, The Role of Space in the Formation of Social Ties, gathered this literature and sorted the ways physical space shapes relationships into three: propinquity, or who is simply near whom; composition, or whether there are fixed places that pull people together; and configuration, or how paths and barriers channel where people go. Salazar-Miranda’s garden city measure is, in those terms, a study of configuration. Winding, disconnected streets are a way of arranging the barriers so that fewer paths cross.

The mechanism has not changed since. Ray Oldenburg’s notion of the “third place,” from his 1989 book The Great Good Place, described the cafés, pubs and corner shops sitting between home and work where someone can become a regular. Robert Putnam, in Bowling Alone, counted sprawl and long commutes among the forces pulling Americans out of shared civic life, estimating that each extra ten minutes of daily commuting came with a measurable drop in local involvement.

The thread running through all of it is unglamorous. Connection is assembled out of repeated, low-stakes, slightly involuntary contact. Remove the occasions and the contact stops, however warm the people involved might be.

Where the design read holds, and where it stops

The strength of this framing is that it lifts the problem off the individual. If you rarely see the people next door, that may say less about your sociability than about a street with no footpath, nothing within walking distance worth walking to, and a garage that absorbs the car before anyone has to step outside. Nobody can will into being the encounters that a layout has quietly deleted.

It is worth holding lightly all the same. The analysis runs on 2019 figures, gathered before COVID-19 rearranged how and where people move, and its isolation measure inherits the known skews of phone-location datasets, which capture some groups far better than others. It covers one country and one design tradition. And it remains a single paper, however well built.

It also does not convert into a personal instruction. Nothing in it says a reader should move to a city, or that packing homes closer together fixes anything on its own. A separate 2024 study in Nature Human Behaviour, led by Timur Abbiasov and co-authored by Salazar-Miranda, used location data from roughly 40 million US devices to measure how much daily activity actually happens within a short walk of home, and found that raising that local share can come with a trade-off: more experienced segregation for lower-income residents. Closer is not automatically better. The argument here is narrower and sturdier: design, not distance and not density by itself, is doing the work, and a dense place laid out badly can isolate its residents as efficiently as a sprawling one.

What the paper offers is a corrective to the habit of treating loneliness as a modern failing of nerve. Temperament plays a part, and so do screens, and so does the ordinary narrowing of adult life. But a sizeable share of it, on this evidence, was set into the ground plan decades ago, in the width of the roads and the direction the front doors face.

A person can learn to be a better neighbour. It is much harder to be one on a street built so that you never meet.