In this chapter, I conduct a within-case analysis of the United States. Unlike Israel, the United States has never been a parliamentary democracy. Instead, it has employed a presidential system of government since its founding. Also in marked contrast to Israel, its electoral system falls on the extremely restrictive end of the continuum: with minor exceptions since the mid-1800s, the electoral system used by the United States at the federal or national level has consisted of single-member districts and a plurality formula, otherwise known as “first past the post.” This makes the United States a good case with which to explore how changes in society have shaped the fragmentation of the party system when the electoral system is majoritarian, this chapter's goal.

What the United States and Israel do have in common, however, is that both have experienced rapid, fairly large-scale change in the composition of their citizenries. Like Israel, the United States is a country of immigration. But immigration has not been the only historical process to increase the social, and specifically the ethnic, heterogeneity of the United States' citizenry: the extension of the franchise to African Americans is another. While immigration has introduced numerous social groups differentiated by various attributes, from language to religion, to the United States, African American enfranchisement has introduced a single social group with an accordingly greater latent capacity for collective action. This is why I turn my lens from the historical process of immigration to the franchise in this within-case analysis of the United States.