Study Finds Urban Highways Can Weaken Social Connection in Cities

Highways are often seen as symbols of efficiency and connection, designed to move people quickly from one place to another. But a new study suggests that in many cities, highways may actually be doing the opposite when it comes to human relationships.

Research published in Proceedings of the National Academy of Sciences (PNAS) finds that urban highways significantly reduce social connections between people who live nearby, especially within distances of less than five kilometers (or about three miles) from the highway. The study shows that while highways can help connect people across longer distances, they often act as physical and social barriers at the neighborhood level.

“In concrete terms, this means that if two people live on different sides of an urban highway, it is less likely that there will be social contact between them,” said lead author Sándor Juhász, a research fellow at Corvinus University of Budapest.

Analyzing Social Connections Across 50 U.S. Cities

The study, led by researchers from the IT University of Copenhagen and the Complexity Science Hub, analyzed social connections across the 50 largest cities in the United States. To do this, researchers combined detailed geographic data with social network information from approximately one million users of X (formerly Twitter). By mapping where people lived and how they were socially connected, the team was able to measure how highways influence social ties within cities.

This approach allowed researchers to quantify a phenomenon that urban planners have long suspected but had never been able to measure at this scale. The results showed that highways consistently reduce social connections at short distances. Only at distances greater than about 20 kilometers (about 12.4 miles) did highways begin to support increased connectivity.

The Barrier Effect

The barrier effect was strongest in Cleveland, Ohio, a city with a long history of segregation tied to infrastructure decisions. Researchers noted that many highways built in the United States during the 1950s and 1960s were routed through densely populated neighborhoods, often dividing communities along racial and economic lines. Detroit’s Eight Mile Road is one of the most well-known examples, where the study found reduced social interaction persists today.

From a Blue Zones perspective, these findings highlight an important truth. Longevity is not just shaped by individual habits, but by the environments where people live. In the world’s longest-lived communities, social connection is woven into daily life through walkable streets, shared community spaces, and frequent face-to-face interaction. When infrastructure makes it harder to cross the street, visit a neighbor, or gather locally, those small daily connections can quietly disappear.

The study also comes at a pivotal moment. While initiatives like the U.S. Department of Transportation’s Reconnecting Communities Pilot (RCP) Program were created to address the social and economic harms caused by highway construction, researchers noted that recent policy changes have paused or ended some of these efforts.

As cities rethink transportation, housing, and public space, the study offers a clear reminder. How we design our communities can either bring people together or pull them apart. And over time, those choices may shape not only how connected we feel, but how long and how well we live.

Rae Bennett is a creative strategist who uses storytelling, design, and digital media to inspire well-being and strengthen community connection. She holds a bachelor’s degree in Communications and Studio Art from Christopher Newport University.