Elections matter in democratic societies. They not only decide who will govern, but they can also reveal, beneath the surface, other important pieces of information about political life. Behind the aggregate total of votes received by each party lies a puzzle: where do the votes come from? The social profile of party electoral coalitions is important because once in power, parties tend to reward their most important supporters. As these profiles change, whether as a result of demographic shifts, declining rates of political participation, or changes in voting behavior, influences on the policies of democratically elected governments change as well.
The study of the "social" bases of voting behavior (and how they change over time) has been an important part of the tradition of voting studies. It is also a central focus of political strategists and campaign managers seeking to maximize candidate and party vote shares. In this essay, we discuss some of the most important changes in voting demographics. To keep the discussion manageable, our focus is on the established "rich" democracies of Western Europe and North America, although many of the same. points could be made about some of the newer democracies in Eastern Europe, Asia, and Latin America.
Elections in the rich democracies during the first three-quarters of the 20th century were defined by fairly stable group-based alignments. Historically, the two most important of these were those based on religion and class, with religion as a generally stronger predictor of voting-behavior. More recently, a gender cleavage has opened up in many countries, with women shifting in significant numbers towards center-left parties. In some places, other.group-based alignments--such as those along linguistic, regional, or racial lines--have also been important, although these have varied from country to country and have not lent themselves to broad generalizations. In the United States, for example, African-American voters have been overwhelmingly Democratic since the early 1960s, representing perhaps the single strongest social group alignment in any of the rich democracies today. Regional and linguistic divides in countries like Canada or Belgium can play an important role. And rising rates of immigration are becoming increasingly significant, especially in countries where immigrants or their children can gain citizenship rights.
The classical theory of group alignments holds that once a group comes to be politically aligned in the party system, that alignment tends to endure and reproduce itself. The logic is that party leaders and candidates make similar group-based appeals and policy commitments at each election that are sufficient to "remind" voters of their usual preferences. But these evidently "settled" questions have become deeply unsettled in recent years. Understanding what these changes are, and how they are impacting elections and a the party systems of democratic polities, is a complicated challenge for scholars, political commentators, and party-strategists alike. We think the best way to unpack this puzzle is by returning to the question posed at the beginning of this essay: where do the votes come from? This in turn can be broken down into three smaller questions: (1) who votes? (2) how are important social groups aligned with parties? and (3) how has the size of key groups (and how they change over time) impacted parties and elections?
In many rich democracies, turnout in national elections is high (80 percent or more). When turnout is very high, turnout rates among groups do not vary much. But it has long been understood that in elections in which turnout is far from universal, resource-rich groups vote at higher rates than more disadvantaged groups. For example, in the United States, where turnout rates in presidential elections have been between 55 percent and 60 percent in recent elections, there is typically a large turnout gap (25 percent or more) between the highest turnout group within a social cleavage category and the lowest (e. …