Where diverse populations gather: Transit accessibility and the spatial structure of social mixing

TL;DR

This study investigates how public transit accessibility influences social mixing at urban venues across different cities, revealing that transit acts as a bridge connecting diverse populations especially in larger metropolitan areas.

Contribution

It provides empirical evidence on the role of transit infrastructure in shaping social mixing patterns and introduces a novel analysis using mobile GPS data across multiple cities.

Findings

Transit accessibility correlates with visitor diversity in large cities.

In smaller Swedish cities, this correlation diminishes after controlling for other factors.

Transit-diversity hotspots are often in lower-diversity venues with specific spatial characteristics.

Abstract

Urban venues serve as arenas for social mixing. While residential and activity-space segregation have been extensively studied, less is known about how the spatial structure of cities, particularly public transit infrastructure, shapes the geography of social mixing at specific locations. This study examines how transit accessibility associates with visitor diversity -- the compositional heterogeneity of visitors sharing a venue, used here as an indicator of social mixing potential -- at points of interest (POIs) in nine cities in Sweden and three cities in the United States (New York, Washington DC, Atlanta). Using mobile phone GPS data in 2024, we compute visitor diversity indices based on the birth background composition of visitors' home neighborhoods. Transit catchment diversity positively predicts visitor diversity, but this association is robust only in the largest metropolitan areas; in smaller Swedish cities, the coefficient attenuates to insignificance once geographic catchment composition, centrality, and venue density are controlled. Transit-diversity hotspots concentrate not in already diverse venues, but in lower-diversity POIs with lower commercial density, greater distance from transit in US cities, and greater centrality in Sweden. These patterns are consistent with transit infrastructure playing a bridging role, linking diverse populations to venues where alternative pathways are limited.