Social capital I: measurement and associations with economic mobility

A third widely discussed concept of social capital is based on levels of civic engagement and pro-social behaviour rather than on the structure of networks. This form of social capital has been measured using self-reported levels of trust, rates of volunteering or rates of membership in local organizations. Such measures are often associated with various outcomes across regions and countries, ranging from economic growth to political accountability.

Because they do not rely on network data, state-level and county-level indices of civic engagement based on survey data are widely available. Here, we build on previous efforts by constructing measures of civic engagement at the more granular ZIP-code level, taking advantage of the large sample sizes available in the Facebook data.

A common way to measure civic engagement is on the basis of rates of volunteering. Building on previous work, we construct a proxy for the rate of volunteering in an area based on the share of Facebook users in that area who are members of at least one volunteering or activism group as classified based on their titles. Such groups include, for example, Neighbors Helping Neighbors or Adopt a Senior (Methods: ‘Measuring civic engagement’). This measure has a population-weighted correlation of 0.58 with survey-based measures of volunteering rates across states from the Social Capital Project, which suggests that it captures a similar concept.

Another prominent measure of civic engagement is the density of civic organizations in a county. We construct a granular measure of the density of civic organizations (for example, non-profits) based on the number of Facebook pages for such organizations in an area divided by its population (Methods: ‘Measuring civic engagement’). Our index has a population-weighted correlation of 0.67 with the Penn State index across counties (Table 1).

Our two measures of civic engagement vary substantially across areas and exhibit similar geographical patterns, with a population-weighted correlation of 0.46 across counties. Rates of volunteering are highest in the Pacific Northwest and lowest in the Southeast (Fig. 2e). Civic organizations are most common in the Rocky Mountains, Pacific Northwest and New England, and least common in parts of the South (Extended Data Fig. 1e). Both measures of civic engagement also vary substantially across ZIP codes within counties (Fig. 2f).

Civic engagement is positively correlated with both measures of network cohesiveness and measures of economic connectedness (Table 1). Most notably, volunteering rates have a correlation of 0.46 with EC across counties.

In summary, the new measures of social capital constructed here underscore the importance of specifying a particular notion of social capital when assessing the level of social capital in a community. This result is in line with previous observations based on ethnographic and theoretical analyses that have illustrated how a single community can exhibit different levels of social capital depending on the concept being measured. For example, one study noted that “since the publication of Stack, sociologists know that everyday survival in less wealthy urban communities frequently depends on close interaction with kin and friends in similar situations. The problem is that such ties seldom reach beyond the inner city, thus depriving their inhabitants of sources of information about employment opportunities elsewhere and ways to attain them”. Our quantitative measures confirm these ethnographic observations in specific communities on a national scale, showing, for example, that high-poverty urban communities with highly cohesive networks often do not provide connections to individuals with high SES.

The benefit of having measures of social capital for all communities in the United States is that they can be used to study which types of social capital matter for various outcomes of interest. In the next section, we investigate which forms of social capital are associated with one prominent outcome that many have hypothesized to rely on social capital: upward economic mobility.