Why do third parties have such a difficult time establishing themselves in the United States?

Question

Quizplus · Accepted Answer

The "first-past-the-post" electoral system used in the United States means that the candidate who receives the most votes in a district wins the election. This system heavily favors the two major parties and makes it difficult for third parties to gain traction because they often do not have the support or financial resources that the two major parties do. In contrast, proportional systems used in other countries give third parties more of a chance to win seats in government.

Why Do Third Parties Have Such a Difficult Time Establishing