Partisan Joiners: Associational Membership and Political Polarization in the United States (1974–2004)*

The academic debate on the impoverishment of political life, increased social isolation, and the threat of authoritarianism reached its height in the 1950s and 1960s, fueled by the dramatic experiences of World War II. A quite heterogeneous group of scholars, drawing from the European experiences of the previous decades and the changing nature of American community, reached discouraging conclusions about the rise of mass society and its consequences for democracy and social stability (Arendt, 1958; Mann, 1970; Kornhauser, 1959; Linz, 1978; see also Mills, [1956] 1970; Converse, 1964; Milgram, 1967). In contrast, theorists of political pluralism suggested that, in practice, representative democracies do not require large levels of mass participation, and that a multitude of interest groups, not an exclusive inner circle, have access to power. In a more optimistic vein, they argued that cross-cutting interests, intergroup competition, and institutional differentiation secure the openness of the democratic process (Truman, 1951; Dahl, 1961; Lowi, [1969] 1979; Galston, 2002). Although animated by less dramatic concerns, over the last two decades sociologists and political scientists have produced ample evidence of the fact that many symptoms of the same (alleged) democratic malaise still affect U.S. society: from the polarization of Congress and the end of the era of bipartisan politics (Brady and Han, 2006; Poole and Rosenthal, 2007), to increasing social and political inequality (McCarty, Poole, and Rosenthal, 2006; Bartels, 2008), to the inconsistent and scarce participation of the mass public (Verba, Schlozman, and Brady, 1995; Delli Carpini and Keeter, 1996; Patterson, 2002), to the decline in associational membership (Putnam, 2000; Skocpol, 2003; but see Minkoff, 1997 and Wuthnow, 2002 for an alternative view, and Fischer, 2009 on social isolation). Nonetheless, in recent years, scholars have failed to systematically relate dynamics of political division and polarization to changes in associational life and civic engagement. Moreover, they have usually assumed that a vivid associational life fosters democratic outcomes—taking for granted that bowling together is better than bowling alone—thus failing to consider the actual consequences of the decline in civic participation on the level of political integration and social cohesion. In this article I examine the interplay between associational membership and political partisanship, and ask if there is any evidence of increased political polarization in the associative patterns of Americans. The goal is to assess to what extent the polarization of party members and political activists is complemented by a similar dynamic in civic life. To address this question, I look at changes over time in the partisanship of associational groups, comparing the partisan allegiances of group members to those of nonmembers, and analyzing the network of interorganizational relations generated by overlapping memberships. Looking at the intersection of different social spheres from a macro perspective, I conclude that U.S. civil society is not becoming more polarized. The analysis shows that the observed decline in civic engagement has not reduced the overall level of integration of civic networks, and that there are no signs of increased polarization in patterns of overlapping memberships: nor do divergent associational patterns emerge when comparing the subpopulations of Democrats and Republicans. Nonetheless, while political partisanship does not drive patterns of group affiliation, group joiners tend to be more partisan than the overall population: group members, especially those belonging to multiple groups, are more radical in their partisan identification than nonmembers, and most types of groups have become politically more heterogeneous over time. To make sense of these findings, in the discussion, I advance the hypothesis that polarization of civil society is occurring at the level of actual groups, and not group types.