Bowling Alone

Robert Putnam's 2000 documentation of the decline in American civic engagement — using 500,000 interviews to show that Americans participate less in civic organizations, trust their neighbors less, and maintain fewer social connections than in previous generations — the most cited political science book of the 2000s.

Creates the social capital decline thesis — Bowling Alone documents systematically (across voting, volunteering, church attendance, club membership, dinner parties, and bowling leagues) that American social capital has been declining since the 1960s, making it the empirical foundation for concerns about American civic decay.