San Francisco's Marina, Castro and Haight neighborhoods are home to the city's most far-flung Facebook friendships, while residents of Bayview-Hunters Point, Visitacion Valley and Ingleside tend to keep their social ties much closer to home. That's according to a new ZIP-code-level breakdown of Facebook's Social Connectedness Index, a dataset that measures how likely people in different places are to be friends on the platform.
The neighborhood findings come from an analysis published by the San Francisco Chronicle, which compared each San Francisco ZIP code's connections to people in other states with the citywide average. The Chronicle found that wealthier San Francisco ZIP codes were more likely to have Facebook friends in other states. The Social Connectedness Index, as described by social-connectedness.org, measures the relative probability that two locations are connected by a Facebook friendship, accounting for how many users live in each place.
Who's Close to Home, and Who Isn't
The Chronicle's analysis also found that the Marina was most connected to North Beach and least connected to Bayview-Hunters Point in comparisons among San Francisco neighborhoods.
More broadly, the Chronicle's analysis found San Franciscans are generally more likely to be friends with people in other Bay Area counties than with people living elsewhere in California. That tracks with how the SCI is built: the index is calculated from the number of Facebook friendship links between two locations divided by the product of their user populations, according to the index's own interactive explorer, so the index generally declines with geographic distance.
Friendship Links Aren't Migration Flows
Other public data measure moves rather than social ties. The IRS bases its migration statistics on year-to-year address changes reported on tax returns. The Census Bureau county-to-county flows compare respondents' current county with the county where they lived one year earlier; its listed series uses the ACS 5-year 2016–2020 dataset. Neither measure tracks Facebook friendship links.
Why the Marina Feels Closer to the East Coast
The Chronicle reported that San Francisco Facebook users were more likely to have friends in New York City's West Village than in any other place outside California. Its analysis also found strong connections between many San Francisco areas and Cambridge, Massachusetts.
The Chronicle's analysis found that San Francisco's eastern half was more likely than its western half to have Facebook friends in Alabama, while the city's north and south sides differed more sharply in their likelihood of having friends in Massachusetts. The analysis compared Facebook friendships by San Francisco ZIP code.
How the Index Actually Works
To build the comparisons, the Chronicle filtered the zip-code-level SCI data down to San Francisco and joined it with population-weighted mean data grouped by state, then compared each ZIP code's index for every state against the average index across all San Francisco ZIP codes. The outlet also examined raw scores to compare relative connectedness between individual San Francisco ZIP codes and other ZIP codes and states nationally.
The underlying dataset reflects an update as of January 25, 2026, described in a working paper by NYU Stern researchers. The paper also reports that counties with a larger share of far-flung friendships tend to be richer, better educated and have higher life expectancy.
The San Francisco-focused analysis was published by the Chronicle.
