Fragmentation of a longitudinal population-scale social network: Decreasing structural social cohesion in the Netherlands

TL;DR

This study analyzes a large-scale social network in the Netherlands from 2010 to 2021, revealing a significant decline in social cohesion driven by network rewiring and mobility, with implications for social policy.

Contribution

It introduces a network-based approach to measure population-scale social cohesion and identifies key mechanisms behind its decline over time.

Findings

Social cohesion declined by over 15% from 2010 to 2021.

Rewiring of individual networks and increased mobility drive cohesion decline.

Residential relocation temporarily increases local social cohesion.

Abstract

Population-level dynamics of social cohesion and its underlying mechanisms remain difficult to study. In this paper, we propose a network approach to measure the evolution of social cohesion at the population scale and identify mechanisms driving the change. We use twelve annual snapshots (2010-2021) of a population-scale social network from the Netherlands linking all residents through family, household, work, school, and neighbor relations. Results show that over this period, social cohesion, quantified as average closure in the network, declines by more than 15%. We demonstrate that the decline is not due to changes in demographic composition, but to rewiring in individual ego networks. Statistical models confirm a decreasing overlap of social contexts and greater geographical mobility as drivers. Residential relocation, however, temporarily increases closure, suggesting that local cohesion-seeking behavior can yield global network fragmentation, with implications for policies related to housing, urban planning, and social integration.