Labor unions pull their membership from various parts of society, and as unions decline, that's one less method for people to rise above segregated views.

..................................................................................................................................
Ahlquist and Levi are the authors of: In the Interest of Others: Organizations and Social Activism, published by Princeton University Press. 
..................................................................................................................................
The decline of union membership and what it means for politics
By John S. Ahlquist and Margaret Levi, October 24, 2013

Our book is about how organized groups define their scope of action.  Can members be persuaded to take actions on behalf of others outside the group?  This is a surprisingly difficult question to answer.  Political parties, religious congregations, and civic associations all man[a]ge to coordinate behavior on behalf of others.  But they also screen actively for like-minded people based on shared political or religious perspectives.  Similarly, individuals regularly sort themselves into groups reflecting their preexisting preferences.  What room is there for persuasion and inspiration?  What leeway is there for organizational leaders to expand the organization’s mandate?

We focus on labor unions, comparing those with minimal political commitments to the very mobilized.  We show that it is possible — though difficult — for these groups to take positions and sustain costly group actions on topics far from the organization’s original raison d’etre. These actions are consistent with what we refer to as a broader “community of fate,” in which the welfare of group members is treated as bound up with that of others outside the group. Expanding the community of fate depends on activist leaders and organizational rules existing in a delicate equilibrium.  The leaders must manage to supply union members the benefits the members expect while also subjecting themselves to constraint and oversight. Key constraints involve limits on the leader’s pay and possible sanction by members, including losing office.  For the constraints to work, the members must be sufficiently informed about policies and events on which they are asked to take stands.

Unions are noteworthy because people join them, in large part, for economic and employment reasons. There is little evidence that workers in the countries we study (Australia and the United States) sort themselves into unions based on the political activities or social stances of the organization.  For their part, industrial unions have incentives to recruit and accept as many workers in their industry as possible, though some have, at times, excluded Communists, women and racial minorities.  The lack of sorting and relatively minimal screening in industrial labor unions is crucial. The resulting heterogeneity within unions requires politically ambitious union leaders to favor organizational rules enhancing communication and credibility.  For union members, the costs to leaving the organization are conducive to what Albert O. Hirschman referred to as voice and loyalty.  Members are willing to go along with the organizational program so long as the decision-making procedure is fair and they get what they signed up for.  The result is a set of formal rules and informal norms to which leaders must adhere if they are to mobilize the members over time.  What we also find, however, is that organizational activism can affect the members as well.

In our research we read the oral histories, combed the archives, surveyed workers and conducted dozens of interviews, revealing numerous instances of union leaders and education committees providing information about events of the day and asking members to get involved.  Let one story from Australia stand for many. A retired Australian dockworker followed us out of the union hall to recount his experience. At a lunchtime union meeting on the docks many years earlier he heard about the Dutch ships coming to Sydney to load arms for use to put down the Indonesian rebellion.  He emphasized that he had never heard of the Indonesian rebellion and was not particularly political.  He did not sympathize with the communism espoused by some of the union leadership of the time.  But when he learned about the Dutch ships he was shocked and the union gave him a way to do something about it.  He joined the union embargo against the Dutch ships. Credible new information and the possibility of action in the context of his union transformed his beliefs about his own political efficacy.

The unions we studied demonstrate how organizations can expand the nature and scope of political action, especially among those for whom politics might otherwise not appear terribly relevant. But the conditions we found in those groups appear increasingly scarce today. Unionization is now a relatively rare thing.  Individuals are sorting themselves into organizations of the like-minded, and our neighborhoods, cities and states are segregated in ways correlated with existing political views.  Some people select media — from a much longer menu — that reinforces, rather than challenges, their existing perspectives, leading to echo chambers and demagoguery.  The decline of labor unions, and the stagnation of encompassing political parties and religious organizations that incorporate differing political perspectives, has been accompanied by the rise of groups focused on special interests and narrowed communities of fate.
..................................................................................................................................