Origins and consequences of long ties in social networks

Social networks play a predominant role in determining how information spreads between individuals. Previous works suggest that long ties, which connect people who do not share any mutual contact, provide access to valuable information on economic opportunities. However, no population-scale study has determined how long ties relate to economic outcomes and how such ties are formed. Using a novel dataset from Facebook, we reconstruct the network of interactions between users and we uncover a strong relationship between the share of long ties and economic outcomes at the local level in the United States and in Mexico. Administrative units with a higher proportion of long ties have higher incomes, higher economic mobility, lower unemployment rates and higher wealth, even after adjusting for potential confounders of these outcomes. In contrast to the weak tie theory, we find that having stronger long ties is associated with better economic outcomes. Furthermore, we discover that users with a higher proportion of long ties are more likely to have migrated between US states, to have transferred to a different high school, and to have attended college outside of their home state. Taken together, these results suggest that long ties contribute to economic prosperity and highlight the role played by disruptive life events in the formation of these ties.