It's not hard to see trends like this and think we've lost something fundamental in the way we relate to our fellow man.
Your charts on social participation recalls what Charles Murray wrote about in Coming Apart. He also discusses about the decline of marriage. He discussed the lack of knowledge and the two different worlds being formed by the elites and working class groups in many respects. I think he was trying to avoid any kind of calls that the differences are attributable to race by limiting his study to whites but his prescriptions apply for everyone. Unfortunately, due to the baggage because of The Bell Curve this notable book per the NY Times is cast aside.
https://en.wikipedia.org/wiki/Coming_Apart_(book)
The book also discussed the concept of Super Zip which had both high average income and college graduation. The Washington Post has the info still up on their site for you to look up. Interesting and I wonder how these correlate to voting and redistricting/gerrymandering.
http://www.washingtonpost.com/sf/local/2013/11/09/washington-a-world-apart/?utm_term=.775378f8cde0
Poll
