Bowling Alone by Robert D. Putnam was published in article form in 1995 and then developed into a book published in 2000. In the ensuing 15 years, there has been a significant growth in internet use, especially of social media.
By many measures, especially voting and other forms of political participation, the decline observed by Putnam has continued. However, there is some evidence that much of political and civic engagement is shifting online and to social media. This has both positive and negative consequences. On the positive side, it means that young people have convenient access to political discourse, and are using social networking as a way to participate in civic life.
There still remain two negatives. The first is that social networks tend to be echo chambers, in which people limit their feeds and other inputs to sources with which they already agree. The second is that electronically mediated interactions can replace face-to-face communal activities.
Whether, over the long term, the transition to a society dominated by electronic modes of interaction leads to more or less social capital is not really certain at this point, as we are still in the middle of a transitional phase.