A study by The Corporation for National and Community Service finds a correlation between longer commute times and decreasing volunteerism. This agrees with a correlation that sociologist Robert Putnam reported in his book on declining social capital: Bowling Alone.
Portland of course was the counter-example in his book. We also have declining average commutes (from 10 miles in 1990 to 7 miles in 2000). And I wonder how the level of activism in our bicycle community might tie into this correlation?