Many Americans complain about the dominance of our two-party system at election time. America is peculiar among democracies with its two-party political system, which is in contrast to the multi-party system that is present in most other democracies. Having a two-party system means that candidates for any elected office, from president on down, are more likely to be successful if they run as a Republican or as a Democrat.
Why does the United States have a two-party system and not a multi-party system? The explanation most often given is because we have single-member, winner-take-all elections in which a candidate with the most votes wins the election. There is no sharing of the victory with any other party or candidates, as there is in some parliamentary systems. Certainly, this model of elections reinforces the idea of a two-party system, but it does not explain why we have only two major parties.
I contend that we have a two-party system because of the consensus of the American people in support of the political institutions and the economic system that we have. Compare this with the French experience. The French still quarrel more than 200 years after their revolution about what kind of political and economic system would best serve their needs. The French have used both proportional representation and single-member district electoral systems to elect the members of their National Assembly. Regardless of the electoral system used, the French multi-party system has remained intact.
As long as the degree of consensus remains strong in support of the political institutions and the kind of economic system that we have, we can expect to be seen as a country with a peculiar party and electoral system.