Final answer:
In addition to the winner-takes-all system, the Electoral College, first-past-the-post voting system, U.S. historical context, and specific election rules contribute to the dominance of two political parties in the U.S.
Step-by-step explanation:
Factors Contributing to the Dominance of Two Political Parties in the U.S.
Besides the winner-takes-all system, several factors contribute to the dominance of two political parties in the United States. One significant factor is the Electoral College, which reinforces the winner-take-all system at a federal level by allocating the majority of a state's electoral votes to the candidate who wins a plurality in that state. The First-past-the-post voting system, also known as plurality voting, is another contributing factor where the candidate with the most votes wins, which discourages third parties by making it difficult to win seats unless they can secure a majority in specific areas.
Moreover, U.S. history plays a role as the country began with two major parties and has largely seen the evolution of these groups rather than the emergence of new powers. Another related aspect is election rules and campaign laws, which create high barriers for third-party candidates, including the challenge of overcoming established party resources and voter reluctance to 'waste' their vote.
Lastly, unlike a proportional representation system which isn't practiced in the U.S., the current voting system does not allocate seats based on the percentage of votes, thereby preventing smaller parties from gaining legislative representation relative to their vote share.