Despite modern technology enabling unprecedented connectivity, societies are increasingly divided—a paradox most evident in the rising polarization of the United States. 

Using survey data from the past 20 years, we observe a significant increase in social connections, likely driven by the spread of social media and digital communication platforms.  To understand how this surge in connectivity enables political division, we present a computational model where individuals adjust their opinions and social ties based on homophily—the tendency to associate with like-minded individuals—forming new friendships or dissolving existing ones depending on agreement or disagreement.

Our model identifies a critical threshold: when the average number of social connections surpasses this point, even small increases in interactions lead to a sudden and significant rise in polarization. Moreover, the model fits the observed data, showing that the increase in social connectivity over time aligns with the rise in polarization, and underscores the importance of social network structures when addressing societal divisions.